Which of the following is not a characteristic of the completely randomized design?
Answer: Populations have equal means
Which of the following is not a characteristic of the completely randomized design?
Answer: Populations have equal means
Answer: Populations have equal means
Which of the following is not a characteristic of Anova?
Which of the following is not a characteristic of Anova?
Answer: Populations have equal means.
ANOVA is a statistical method for verifying the equality between
ANOVA is a statistical method for verifying the equality between
Answer: some population means
A random variable having an F distribution may assume
A random variable having an F distribution may assume
Answer: any non-negative value
XYZ Company claims to develop an additive which significantly improves gas mileage. Thirty participants were asked to drive first using a standard gasoline, and then drive using this gasoline with the additive. Data was collected for each participant's gas mileages. Which of the following Excel tests is appropriate to test the effectiveness of the additive?
XYZ Company claims to develop an additive which significantly improves gas mileage. Thirty participants were asked to drive first using a standard gasoline, and then drive using this gasoline with the additive. Data was collected for each participant's gas mileages. Which of the following Excel tests is appropriate to test the effectiveness of the additive?
Answer: t-Test: Paired Two Sample for Means
When each data value in one sample is matched with a corresponding data value in another sample, the samples are known as
When each data value in one sample is matched with a corresponding data value in another sample, the samples are known as
Answer: matched samples
The standard error of x ̅_1-x ̅_2 is
The standard error of x ̅_1-x ̅_2 is
Answer: the estimated standard deviation of x ̅_1-x ̅_2
If two independent sufficiently large samples are taken from two populations with known population standard deviations, the sampling distribution of the difference, x ̅_1-x ̅_2, between the two sample means x ̅_1 and x ̅_2
If two independent sufficiently large samples are taken from two populations with known population standard deviations, the sampling distribution of the difference, x ̅_1-x ̅_2, between the two sample means x ̅_1 and x ̅_2
Answer: can be approximated by a normal distribution
The lift ratio of an association rule with a confidence value of 0.88 and in which the consequent occurs in 60 out of 100 cases is:
The lift ratio of an association rule with a confidence value of 0.88 and in which the consequent occurs in 60 out of 100 cases is:
Answer: 1.47
In the theory of association rules in data mining, by confidence we mean an estimated probability that
In the theory of association rules in data mining, by confidence we mean an estimated probability that
Answer: the consequent occurs given that the antecedent occurs
A _____ refers to the number of times that a collection of items occur together in a transaction data set.
A _____ refers to the number of times that a collection of items occur together in a transaction data set.
Answer: support count
An analysis of items frequently co-occurring in transactions (such as purchases) is known as _____.
An analysis of items frequently co-occurring in transactions (such as purchases) is known as _____.
Answer: market basket analysis
The endpoint of a k-means clustering algorithm occurs when:
The endpoint of a k-means clustering algorithm occurs when:
Answer: no further changes are observed in cluster structure and number.
If the Euclidean distance were to be represented in a right triangle, which of the following would be considered the distance between two observations?
If the Euclidean distance were to be represented in a right triangle, which of the following would be considered the distance between two observations?
Answer: the hypotenuse
A tree diagram used to illustrate the sequence of nested clusters produced by hierarchical clustering is known as a _____.
A tree diagram used to illustrate the sequence of nested clusters produced by hierarchical clustering is known as a _____.
Answer: dendrogram
_____ is the vector of the averages computed for each variable across all cluster observations.
_____ is the vector of the averages computed for each variable across all cluster observations.
Answer: Centroid
_____ measures dissimilarity between two clusters by using the distance between the two cluster centroids.
_____ measures dissimilarity between two clusters by using the distance between the two cluster centroids.
Answer: Centroid linkage
Average group linkage measures dissimilarity between two clusters by considering:
Average group linkage measures dissimilarity between two clusters by considering:
Answer: the average distance over all pairs of observations between these clusters.
_ measures dissimilarity between two clusters by considering only the two most distant observations in these clusters.
_ measures dissimilarity between two clusters by considering only the two most distant observations in these clusters.
Answer: Complete linkage
Single linkage measures dissimilarity between two clusters by considering:
Single linkage measures dissimilarity between two clusters by considering:
Answer: only the two closest observations in these clusters.
Jaccard's coefficient is different from the matching coefficient in that the former:
Jaccard's coefficient is different from the matching coefficient in that the former:
Answer: does not count matching zero entries while the latter does.
The simplest measure of similarity between observations consisting solely of categorical variables is given by _____.
The simplest measure of similarity between observations consisting solely of categorical variables is given by _____.
Answer: matching coefficient
The k-means clustering is the process of
The k-means clustering is the process of
Answer: organizing observations into one of k groups based on a measure of similarity.
Which of the following is true of bottom-up hierarchical clustering?
Which of the following is true of bottom-up hierarchical clustering?
Answer: It starts with each observation in its own cluster and then iteratively combine two most similar clusters
The data-mining method that can be used in market segmentation to divide consumers into different homogeneous groups is _____.
The data-mining method that can be used in market segmentation to divide consumers into different homogeneous groups is _____.
Answer: cluster analysis
_____ is a category of data-mining techniques that detect patterns and relationships in the data.
_____ is a category of data-mining techniques that detect patterns and relationships in the data.
Answer: Descriptive data-mining
Observation refers to the:
Observation refers to the:
Answer: set of recorded values of variables associated with a single entity.
Which of the following reasons is responsible for the increase in the use of data-mining tech-niques in business?
Which of the following reasons is responsible for the increase in the use of data-mining tech-niques in business?
Answer: The ability to electronically warehouse data
A monthly time series has a seasonal pattern. If a linear regression model is used, how many dummy variables must be used to represent this seasonality?
A monthly time series has a seasonal pattern. If a linear regression model is used, how many dummy variables must be used to represent this seasonality?
Answer: 11
Which of the following statements is the objective of the moving averages and exponential smoothing methods?
Which of the following statements is the objective of the moving averages and exponential smoothing methods?
Answer: To smooth out random fluctuations in the time series
For a quarterly time series over the last 4 years, the following linear trend expression was estimated:
For a quarterly time series over the last 4 years, the following linear trend expression was estimated:
y ̂_t = 120 + 2t. The forecast for the second quarter of Year 5 is
156
For a time series with 17 time periods, the following linear trend expression was estimated:
For a time series with 17 time periods, the following linear trend expression was estimated:
Answer:
y ̂_t = 129.2 + 3.8t. The forecast for time period 18 is
197.6
One measure of the accuracy of a forecasting model is
One measure of the accuracy of a forecasting model is
Answer: the mean square error
Which of the following data patterns best describes the scenario shown in the below plot?
Which of the following data patterns best describes the scenario shown in the below plot?
Answer: Time series with a horizontal pattern
Which of the following data patterns best describes the scenario shown in the given quarterly time series plot?
Which of the following data patterns best describes the scenario shown in the given quarterly time series plot?
Answer: Seasonal pattern
A method that uses a weighted average of all past values is known as
A method that uses a weighted average of all past values is known as
Answer: an exponential smoothing
If data for a time series analysis is collected on an annual basis only, which pattern may be ignored?
If data for a time series analysis is collected on an annual basis only, which pattern may be ignored?
Answer: seasonal
The pattern of a time series in business forecasting that is most difficult to predict is
The pattern of a time series in business forecasting that is most difficult to predict is
Answer: cyclical pattern
The time series pattern that reflects gradual increase or decrease in values over a long time period is called
The time series pattern that reflects gradual increase or decrease in values over a long time period is called
Answer: a trend
The time series pattern that reflects variability during a single year is called
The time series pattern that reflects variability during a single year is called
Answer: seasonal
The time series pattern which reflects a multi-year pattern of being above and below the trend line is
The time series pattern which reflects a multi-year pattern of being above and below the trend line is
Answer: cyclical
A group of observations measured at successive time intervals is known as
A group of observations measured at successive time intervals is known as
Answer: a time series
_____ is a generalization of linear regression for predicting an outcome of a binary variable.
_____ is a generalization of linear regression for predicting an outcome of a binary variable.
Answer: Logistic regression
In the k-nearest neighbors method, when the value of k is set to 1,
In the k-nearest neighbors method, when the value of k is set to 1,
Answer: the classification or prediction of a new observation is based solely on the single most similar observation from the training set.
An observation is classified as Class 1 if
An observation is classified as Class 1 if
Answer: the predicted probability of this observation to be in Class 1 is greater than or equal to the cutoff value
Test set is the data set used to:
Test set is the data set used to:
Answer: estimate accuracy of final model on unseen data.
The effectiveness of a classification method can be judged by computing the misclassification errors and summarizing them in a
The effectiveness of a classification method can be judged by computing the misclassification errors and summarizing them in a
Answer: confusion matrix
In classification, which of the following would be considered as a categorical variable for a credit approval decision for a requester?
In classification, which of the following would be considered as a categorical variable for a credit approval decision for a requester?
Answer: reject or accept credit approval
_____ is the process of estimating the value of a categorical outcome variable.
_____ is the process of estimating the value of a categorical outcome variable.
Answer: Classification
Within a given range of cells, the number of times a particular condition is satisfied is computed by using the _____ function.
Within a given range of cells, the number of times a particular condition is satisfied is computed by using the _____ function.
Answer: COUNTIF
The arguments supplied to the IF function are:
The arguments supplied to the IF function are:
Answer: the condition for execution, the result if condition is true, and the result if condition is false.
The _____ function pairs each element of the first array with its counterpart in the second array, multiplies the elements of the pairs together, and adds the results.
The _____ function pairs each element of the first array with its counterpart in the second array, multiplies the elements of the pairs together, and adds the results.
Answer: SUMPRODUCT
The impact of two inputs on the output of interest can be examined by a _____.
The impact of two inputs on the output of interest can be examined by a _____.
Answer: two-way data table
A one-way data table summarizes:
A one-way data table summarizes:
Answer: a single input's impact on the output of interest.
A(n) _____ refers to a model input that the decision maker can control in a what-if model.
A(n) _____ refers to a model input that the decision maker can control in a what-if model.
Answer: decision variable
With reference to a what-if model, an uncontrollable model input is known as a(n) _____.
With reference to a what-if model, an uncontrollable model input is known as a(n) _____.
Answer: parameter
Which of the following approaches is a good way to proceed with the influence diagram building for a problem?
Which of the following approaches is a good way to proceed with the influence diagram building for a problem?
Answer: The influence diagram for a portion of the problem is build first and then expanded until the total problem is conceptually modeled.
A(n) _____ is a visual representation that shows which entities influence others in a model.
A(n) _____ is a visual representation that shows which entities influence others in a model.
Answer: influence diagram
The modeling process begins with the framing of the _____ that shows the relationships between the various parts of the problem being modeled.
The modeling process begins with the framing of the _____ that shows the relationships between the various parts of the problem being modeled.
Answer: conceptual model
In _____ decision making companies have to decide whether they should manufacture a product or outsource its production to another firm.
In _____ decision making companies have to decide whether they should manufacture a product or outsource its production to another firm.
Answer: make-versus-buy
Spreadsheet models are referred to as what-if models because they
Spreadsheet models are referred to as what-if models because they
Answer: allow easy instantaneous recalculation for a change in model inputs.
The probabilities of states of nature after revising the prior probabilities based on given sample information are called
The probabilities of states of nature after revising the prior probabilities based on given sample information are called
Answer: the posterior probabilities
Prior probabilities are the probabilities of the states of nature that are estimated
Prior probabilities are the probabilities of the states of nature that are estimated
Answer: before obtaining sample information
Nodes of a decision tree indicating points where the outcomes do not depend on a decision maker are known as
Nodes of a decision tree indicating points where the outcomes do not depend on a decision maker are known as
Answer: chance nodes
Nodes of a decision tree indicating points where a decision maker chooses a decision alternative are known as
Nodes of a decision tree indicating points where a decision maker chooses a decision alternative are known as
Answer: decision nodes
A graphic presentation of the expected gain from the various options open to the decision maker is called
A graphic presentation of the expected gain from the various options open to the decision maker is called
Answer: a decision tree
A tabular representation of gains or losses for a decision problem is called a
A tabular representation of gains or losses for a decision problem is called a
Answer: payoff table
The uncontrollable future events that affect the outcome of a decision are known as
The uncontrollable future events that affect the outcome of a decision are known as
Answer: states of nature
Studies have suggested that compounds in broccoli might combat the effects of overexposure to ultraviolet radiation. We conduct an experiment to determine whether a cream consisting of a broccoli extract reduces sunburn pain. Sixty patients suffering from pain from severe sunburn are available. What is a good way to conduct the experiment?
Studies have suggested that compounds in broccoli might combat the effects of overexposure to ultraviolet radiation. We conduct an experiment to determine whether a cream consisting of a broccoli extract reduces sunburn pain. Sixty patients suffering from pain from severe sunburn are available. What is a good way to conduct the experiment?
A.
Give the cream to all 60 patients, and record their responses.
B.
Divide the patients randomly into three groups of 20 patients each. Give one group the cream, another group an over-the-counter sunburn relief product, and the last group a placebo. Record the responses.
C.
Give some patients the cream and others the placebo, being sure to inform the patients which treatment they are receiving. Record the responses.
Answer: B.
Divide the patients randomly into three groups of 20 patients each. Give one group the cream, another group an over-the-counter sunburn relief product, and the last group a placebo. Record the responses.
The National Institutes of Health is at last sponsoring proper clinical trials of some natural remedies. In one study at Duke University, 330 patients with mild depression are enrolled in a trial to compare Saint-John's-wort with a placebo and with Zoloft, a common prescription drug for depression. The Beck Depression Inventory is a common instrument that rates the severity of depression on a 0 to 3 scale. Identify the completely randomized clinical trial for this study.
The National Institutes of Health is at last sponsoring proper clinical trials of some natural remedies. In one study at Duke University, 330 patients with mild depression are enrolled in a trial to compare Saint-John's-wort with a placebo and with Zoloft, a common prescription drug for depression. The Beck Depression Inventory is a common instrument that rates the severity of depression on a 0 to 3 scale.
Identify the completely randomized clinical trial for this study.
A.
Create pairs of similar subjects and randomly assign one of the treatments to each subject in a group.
B.
Create groups of subjects in increasing order of the severity of depression and assign subjects randomly to each treatment within each group.
C.
Randomly divide subjects into three groups, each consisting of 110 subjects. Assign each group to one of the treatments. Observe change in Beck Inventory score.
Answer: C.
Randomly divide subjects into three groups, each consisting of 110 subjects. Assign each group to one of the treatments. Observe change in Beck Inventory score.
Identify the randomization for a matched pairs design to compare the strength of the right and left hands, using 10 right-handed people as subjects.
An experiment was conducted to determine if the right hand is generally stronger than the left in right-handed people. Hand strength can be crudely measured by placing a bathroom scale on a shelf with the end protruding and then squeezing the scale between the thumb below and the four fingers above. The reading of the scale shows the force exerted.
A.
Create two groups and ask the subjects in each group to use one of the hands to squeeze the scale. Use a coin to decide which subject in a group will use which hand.
B.
Ask each subject to squeeze the scale using both hands, one after the other. Toss a coin to decide which hand they should use first.
C.
Divide all subjects randomly into two groups and ask subjects in each group to use either hand.
Answer: B.
Ask each subject to squeeze the scale using both hands, one after the other. Toss a coin to decide which hand they should use first.
Identify the randomization for a matched pairs design to compare the strength of the right and left hands, using 10 right-handed people as subjects.
A.
Create two groups and ask the subjects in each group to use one of the hands to squeeze the scale. Use a coin to decide which subject in a group will use which hand.
B.
Ask each subject to squeeze the scale using both hands, one after the other. Toss a coin to decide which hand they should use first.
C.
Divide all subjects randomly into two groups and ask subjects in each group to use either hand.
Answer: B.
Ask each subject to squeeze the scale using both hands, one after the other. Toss a coin to decide which hand they should use first.
What cautions do you draw from the US example, which also apply to an experiment on the effects of running lights in Canada?
Cars sold in the United States since 1986 have been required to have a high center brake light in addition to the usual two brake lights at the rear of the vehicle. This safety requirement was justified by randomized comparative experiments with fleets of rental and business cars. The experiments showed that the third brake light reduced rear-end collisions by as much as 50%. After almost a decade in actual use, the Insurance Institute found only a 5% reduction in rear-end collisions, helpful but much less than the experiments predicted. Most cars did not have the extra brake light when the experiments were carried out, so it caught the eye of following drivers. Now that almost all cars have the third light, it no longer captures attention.
Canada too now requires that cars be equipped with "daytime running lights," headlights that automatically come on at a low level when the car is started. Some manufacturers are now equipping cars sold in the United States with running lights.
A.
In the US, most cars did not have the extra brake light when the experiment was carried out. If people in Canada are more willing to coordinate, the results can be in favor of daytime running lights.
B.
Owing to the difference in topography, the results may be different.
C.
The effect of running lights may be lessened when (if) they become common enough that people no longer notice them.
Answer: C.
The effect of running lights may be lessened when (if) they become common enough that people no longer notice them.
Canada too now requires that cars be equipped with "daytime running lights," headlights that automatically come on at a low level when the car is started. Some manufacturers are now equipping cars sold in the United States with running lights.
What cautions do you draw from the US example, which also apply to an experiment on the effects of running lights in Canada?
A.
In the US, most cars did not have the extra brake light when the experiment was carried out. If people in Canada are more willing to coordinate, the results can be in favor of daytime running lights.
B.
Owing to the difference in topography, the results may be different.
C.
The effect of running lights may be lessened when (if) they become common enough that people no longer notice them.
Answer: C.
The effect of running lights may be lessened when (if) they become common enough that people no longer notice them.
How many batches of peanut brittle are needed for the experiment?
A food scientist wants to study the effect of the type of pan and the amount of sodium bicarbonate used in preparing peanut brittle on the flavor of the peanut brittle. In an experiment, peanut brittle is baked in four types of pans: iron, aluminum, stainless steel, and nonstick stainless steel. Sodium bicarbonate is used in three different quantities in the recipe: 0, 2, and 4 grams. Ten batches of peanut brittle are prepared at each combination of pan type and the amount of sodium bicarbonate. A panel of tasters scores each batch on the intensity of peanut, sweet, and buttery flavors.
A.
40
B.
120
C.
30
Answer: B.
120
How many batches of peanut brittle are needed for the experiment?
A.
40
B.
120
C.
30
Answer: B.
120
The progress of a type of cancer differs in women and men. A clinical experiment to compare four therapies for this cancer therefore treats sex as a blocking variable. 500 male and 300 female patients have agreed to act as subjects. Which of the following approaches will you use to create a block design for the experiment?
The progress of a type of cancer differs in women and men. A clinical experiment to compare four therapies for this cancer therefore treats sex as a blocking variable.
500 male and 300 female patients have agreed to act as subjects. Which of the following approaches will you use to create a block design for the experiment?
A.
Observe the current state of cancer. Split the subjects into two groups using sex as the blocking variable and then randomly assign subjects in each group into four sub-groups. Assign each sub-group to one of the treatments. Observe the progress of cancer.
B.
Observe the current state of cancer. Randomly assign subjects to two groups and using sex as the blocking variable, split each group to two sub-groups. Assign each sub-group to one of the treatments. Observe the progress of cancer.
C.
Observe the current state of cancer. Assign the subjects to the four treatments in one randomization. Observe the progress of cancer for male and female subjects.
Answer: A.
Observe the current state of cancer. Split the subjects into two groups using sex as the blocking variable and then randomly assign subjects in each group into four sub-groups. Assign each sub-group to one of the treatments. Observe the progress of cancer.
Researchers conducted an experiment to compare the effects of a carbohydrate-restricted diet (low-carb diet) and a calorie- and fat-restricted diet (low-fat diet) on weight loss. The researchers are concerned that the effect of diet may depend on gender, so sex is treated as a blocking variable. There are 122 severely obese individuals available for the study, 52 of whom are men and 70 of whom are women. Identify the most appropriate experiment design for the experiment.
Researchers conducted an experiment to compare the effects of a carbohydrate-restricted diet (low-carb diet) and a calorie- and fat-restricted diet (low-fat diet) on weight loss. The researchers are concerned that the effect of diet may depend on gender, so sex is treated as a blocking variable. There are 122 severely obese individuals available for the study, 52 of whom are men and 70 of whom are women.
Identify the most appropriate experiment design for the experiment.
A.
Randomly assign all subjects to two groups. Next, split each group into two sub-groups by sex. Next, assign one sub-group to low-carb diet and the other sub-group to the low-fat diet in both the groups. Compare weight loss within the groups.
B.
Use a coin to decide which subject receives which treatment. Divide subjects into two groups depending on which treatment they are receiving. Next, split each group into two sub-groups by sex. Compare weight loss within the groups.
C.
Split the subjects into two groups by sex. Create two sub-groups each in the two groups by random assignment. Next, within each group, assign one sub-group to low-carb diet and the other sub-group to the low-fat diet. Compare weight loss within the groups.
Answer: C.
Split the subjects into two groups by sex. Create two sub-groups each in the two groups by random assignment. Next, within each group, assign one sub-group to low-carb diet and the other sub-group to the low-fat diet. Compare weight loss within the groups.
Identify a lurking variable that may be confounded with the choice of anesthetic in surgery and that could explain the different death rates.
The death rates of surgical patients differ for operations in which different anesthetics are used. An observational study found these death rates for four anesthetics:
Anesthetic: Halothane Pentothal Cyclopropane Ether
Death rate: 1.7% 1.7% 3.4% 1.9%
This is not good evidence that cyclopropane is more dangerous than the other anesthetics.
A.
Financial background of the patient
B.
Types of surgical instruments
C.
Physical condition of the patient
Answer: C.
Physical condition of the patient
Anesthetic: Halothane Pentothal Cyclopropane Ether
Death rate: 1.7% 1.7% 3.4% 1.9%
This is not good evidence that cyclopropane is more dangerous than the other anesthetics.
Identify a lurking variable that may be confounded with the choice of anesthetic in surgery and that could explain the different death rates.
A.
Financial background of the patient
B.
Types of surgical instruments
C.
Physical condition of the patient
Answer: C.
Physical condition of the patient
Which of the following statements correctly describes the meaning of "no statistically significant differences"?
A study, mandated by Congress when it passed No Child Left Behind in 2002, evaluated 15 reading and math software products used by 9424 students in 132 schools across the country during the 2004-2005 school year. It is the largest study that has compared students who received the technology with those who did not, as measured by their scores on standardized tests. There were no statistically significant differences between students who used software and those who did not.
A.
There was no difference in the scores of students who used software and those who did not.
B.
There was a large difference in the scores of students who used software and those who did not. This difference could not have occurred by chance.
C.
There almost certainly was some difference in the scores of students who used software and those who did not. However, the difference was so small that it may have been due to chance alone.
Answer: C.
There almost certainly was some difference in the scores of students who used software and those who did not. However, the difference was so small that it may have been due to chance alone.
Which of the following statements correctly describes the meaning of "no statistically significant differences"?
A.
There was no difference in the scores of students who used software and those who did not.
B.
There was a large difference in the scores of students who used software and those who did not. This difference could not have occurred by chance.
C.
There almost certainly was some difference in the scores of students who used software and those who did not. However, the difference was so small that it may have been due to chance alone.
Answer: C.
There almost certainly was some difference in the scores of students who used software and those who did not. However, the difference was so small that it may have been due to chance alone.
A manufacturer of chisels is interested in determining how the angle at which the cutting edge is sharpened affects tool abrasion. To answer this question, engineers obtain 20 similar chisels. They sharpen five chisels at each of 22.5, 25, 27.5, and 30 degrees. Then, they measure the amount of abrasion (rated on a scale of 1 to 10, with 10 being the worst) after cutting several mortises (square holes) in 3/4-inch hard maple boards.
A manufacturer of chisels is interested in determining how the angle at which the cutting edge is sharpened affects tool abrasion. To answer this question, engineers obtain 20 similar chisels. They sharpen five chisels at each of 22.5, 25, 27.5, and 30 degrees. Then, they measure the amount of abrasion (rated on a scale of 1 to 10, with 10 being the worst) after cutting several mortises (square holes) in 3/4-inch hard maple boards.
Identify the response variable in the given study.
A.
Mortises
B.
Amount of abrasion
C.
Cutting edge
Answer: B.
Amount of abrasion
What is the meaning of the term "significantly" in "significantly fewer heart attacks"?
Can aspirin help prevent heart attacks? The Physicians' Health Study, a large medical experiment involving 22,000 male physicians, attempted to answer this question. One group of about 11,000 physicians took an aspirin every second day, while the rest took a placebo. After several years, the study found that subjects in the aspirin group had significantly fewer heart attacks than subjects in the placebo group.
A.
It means "definitely occurred by chance if there was no difference between the aspirin and placebo groups."
B.
It means "likely to have occurred by chance if there was no difference between the aspirin and placebo groups."
C.
It means "definitely could not have occurred by chance if there was no difference between the aspirin and placebo groups."
D.
It means "unlikely to have occurred by chance if there was no difference between the aspirin and placebo groups."
Answer: D.
It means "unlikely to have occurred by chance if there was no difference between the aspirin and placebo groups."
What is the meaning of the term "significantly" in "significantly fewer heart attacks"?
A.
It means "definitely occurred by chance if there was no difference between the aspirin and placebo groups."
B.
It means "likely to have occurred by chance if there was no difference between the aspirin and placebo groups."
C.
It means "definitely could not have occurred by chance if there was no difference between the aspirin and placebo groups."
D.
It means "unlikely to have occurred by chance if there was no difference between the aspirin and placebo groups."
Answer: D.
It means "unlikely to have occurred by chance if there was no difference between the aspirin and placebo groups."
Further study of the data showed that this conclusion was wrong. The extra deaths among patients treated with the new method could be explained by lurking variables. Identify a lurking variable that might be confounded with a doctor's choice of surgical or nonsurgical treatment.
A large study used records from Canada's national health care system to compare the effectiveness of two ways to treat prostate disease. The two treatments are traditional surgery and a new method that does not require surgery. The records described many patients whose doctors had chosen one or the other method. The study found that patients treated by the new method were significantly more likely to die within eight years.
Further study of the data showed that this conclusion was wrong. The extra deaths among patients treated with the new method could be explained by lurking variables.
A.
Choice of the patient's relatives
B.
Non-availability of surgical instruments
C.
Patient's chance of survival
Answer: C.
Patient's chance of survival
Further study of the data showed that this conclusion was wrong. The extra deaths among patients treated with the new method could be explained by lurking variables.
Identify a lurking variable that might be confounded with a doctor's choice of surgical or nonsurgical treatment.
A.
Choice of the patient's relatives
B.
Non-availability of surgical instruments
C.
Patient's chance of survival
Answer: C.
Patient's chance of survival
Which of the following statements is correct with reference to the two studies?
Does regular exercise reduce bone loss in postmenopausal women? Here are two ways to study this question.
• A researcher finds 1000 postmenopausal women who exercise regularly. She matches each with a similar postmenopausal woman who does not exercise regularly, and she follows both groups for 5 years.
• Another researcher finds 2000 postmenopausal women who are willing to participate in a study. She assigns 1000 of the women to a regular program of supervised exercise. The other 1000 continue their usual habits. The researcher follows both groups for 5 years.
A.
Only the second study will produce trustworthy data.
B.
Both of the studies will produce trustworthy data.
C.
Only the first study will produce trustworthy data.
D.
Neither of the studies will produce trustworthy data.
Answer: B.
Both of the studies will produce trustworthy data.
• A researcher finds 1000 postmenopausal women who exercise regularly. She matches each with a similar postmenopausal woman who does not exercise regularly, and she follows both groups for 5 years.
• Another researcher finds 2000 postmenopausal women who are willing to participate in a study. She assigns 1000 of the women to a regular program of supervised exercise. The other 1000 continue their usual habits. The researcher follows both groups for 5 years.
Which of the following statements is correct with reference to the two studies?
A.
Only the second study will produce trustworthy data.
B.
Both of the studies will produce trustworthy data.
C.
Only the first study will produce trustworthy data.
D.
Neither of the studies will produce trustworthy data.
Answer: B.
Both of the studies will produce trustworthy data.
Which of the following statements describes an appropriate design for this randomized comparative experiment?
A large study used records from Canada's national health care system to compare the effectiveness of two ways to treat prostate disease. The two treatments are traditional surgery and a new method that does not require surgery. The records described many patients whose doctors had chosen one or the other method. The study found that patients treated by the new method were significantly more likely to die within eight years.
You have 300 prostate patients who are willing to serve as subjects in an experiment to compare the two methods.
A.
Assign the nonsurgical treatment to all patients and observe recovery. Then, assign the surgical treatment to the patients who do not recover and again observe recovery.
B.
Ask the patients to select the treatment method they want and divide them into two groups, one group with patients going for surgical treatment and the other group for nonsurgical treatment. Compare the recovery of patients in each group.
C.
Make two groups of 150 patients each by using random assignment. Give the surgical treatment to one group and the nonsurgical treatment to the other group. Observe the recovery of patients in each group.
Answer: C.
Make two groups of 150 patients each by using random assignment. Give the surgical treatment to one group and the nonsurgical treatment to the other group. Observe the recovery of patients in each group.
You have 300 prostate patients who are willing to serve as subjects in an experiment to compare the two methods.
Which of the following statements describes an appropriate design for this randomized comparative experiment?
A.
Assign the nonsurgical treatment to all patients and observe recovery. Then, assign the surgical treatment to the patients who do not recover and again observe recovery.
B.
Ask the patients to select the treatment method they want and divide them into two groups, one group with patients going for surgical treatment and the other group for nonsurgical treatment. Compare the recovery of patients in each group.
C.
Make two groups of 150 patients each by using random assignment. Give the surgical treatment to one group and the nonsurgical treatment to the other group. Observe the recovery of patients in each group.
Answer: C.
Make two groups of 150 patients each by using random assignment. Give the surgical treatment to one group and the nonsurgical treatment to the other group. Observe the recovery of patients in each group.
Which of the following is the explanatory variable in the given study?
A manufacturer of chisels is interested in determining how the angle at which the cutting edge is sharpened affects tool abrasion. To answer this question, engineers obtain 20 similar chisels. They sharpen five chisels at each of 22.5, 25, 27.5, and 30 degrees. Then, they measure the amount of abrasion (rated on a scale of 1 to 10, with 10 being the worst) after cutting several mortises (square holes) in 3/4-inch hard maple boards.
A.
Tool abrasion
B.
Mortises
C.
Sharpening of chisels
D.
Angle of cutting edge
Answer: D.
Angle of cutting edge
Which of the following is the explanatory variable in the given study?
A.
Tool abrasion
B.
Mortises
C.
Sharpening of chisels
D.
Angle of cutting edge
Answer: D.
Angle of cutting edge
The study is not an experiment because no treatment is actively imposed, and the patients or their doctors selected the treatment to be used.
What is the preferred treatment for breast cancer that is detected in its early stages? The most common treatment was once removal of the breast. It is now usual to remove only the tumor and nearby lymph nodes, followed by radiation. To study whether these treatments differ in their effectiveness, a medical team examines the records of 25 large hospitals and compares the survival times after surgery of all women who have had either treatment.
True or false:
True
False
Answer: True
True or false:
The study is not an experiment because no treatment is actively imposed, and the patients or their doctors selected the treatment to be used.
True
False
Answer: True
What is the preferred treatment for breast cancer that is detected in its early stages? The most common treatment was once removal of the breast. It is now usual to remove only the tumor and nearby lymph nodes, followed by radiation. To study whether these treatments differ in their effectiveness, a medical team examines the records of 25 large hospitals and compares the survival times after surgery of all women who have had either treatment.
What is the preferred treatment for breast cancer that is detected in its early stages? The most common treatment was once removal of the breast. It is now usual to remove only the tumor and nearby lymph nodes, followed by radiation. To study whether these treatments differ in their effectiveness, a medical team examines the records of 25 large hospitals and compares the survival times after surgery of all women who have had either treatment.
Identify the explanatory and response variables in this study.
A.
Explanatory variable: Treatment method; Response variable: Survival times
B.
Explanatory variable: Removal or non-removal of breast; Response variable: Women with breast cancer
C.
Explanatory variable: Survival times; Response variable: Treatment method
D.
Explanatory variable: Women with breast cancer: Response variable: Removal or non-removal of breast
Answer: A.
Explanatory variable: Treatment method; Response variable: Survival times
Like an Simple Random Sample (SRS), a systematic sample gives all individuals the same chance to be chosen.
The following example illustrates the idea of a systematic sample. Suppose that we must choose 4 rooms out of the 100 rooms in a dormitory. Because 100/4 = 25, we can think of the list of 100 rooms as four lists of 25 rooms each. Choose 1 of the first 25 rooms at random, using Table A. The sample will contain this room and the rooms 25, 50, and 75 places down the list from it. If 13 is chosen, for example, then the systematic random sample consists of the rooms numbered 13, 38, 63, and 88. Use Table A to choose a systematic random sample of 5 rooms from a list of 200.
True or False:
A systematic sample is, however, not an SRS.
True
False
Answer: True
True or False:
Like an Simple Random Sample (SRS), a systematic sample gives all individuals the same chance to be chosen.
A systematic sample is, however, not an SRS.
True
False
Answer: True
Which of the following sources of error do you think has been included in this reported margin of error?
According to a March 2007 USA Today/Gallup Poll, 43% of Americans identify themselves as baseball fans. That is low by recent standards, as an average of 49% of Americans have said they were fans of the sport since Gallup started tracking this measure in 1993. The high point came in 1998, when Sammy Sosa and Mark McGwire pursued (and ultimately surpassed) Roger Maris's single-season home run record, at which time 56% of Americans considered themselves baseball fans. The Gallup press release says: "For results based on this sample, one can say with 95% confidence that the maximum error attributable to sampling and other random effects is ±3 percentage points."
A.
Voluntary response
B.
Undercoverage
C.
Nonresponse
D.
Random sampling error
Answer: D.
Random sampling error
Which of the following sources of error do you think has been included in this reported margin of error?
A.
Voluntary response
B.
Undercoverage
C.
Nonresponse
D.
Random sampling error
Answer: D.
Random sampling error
When the Current Population Survey asked the adults in its sample of 50,000 households if they voted in the 2000 presidential election, 55% said they had. The margin of error was less than 1%. But, as a matter of fact, only 51% of the adult population voted in that election. Why do you think the CPS result missed by much more than the margin of error?
When the Current Population Survey asked the adults in its sample of 50,000 households if they voted in the 2000 presidential election, 55% said they had. The margin of error was less than 1%. But, as a matter of fact, only 51% of the adult population voted in that election.
Why do you think the CPS result missed by much more than the margin of error?
A.
The margin of error accounts for random sampling error only.
B.
The margin for error is not a suitable measure of sampling error.
C.
The margin of error is incorrectly calculated.
Answer: A.
The margin of error accounts for random sampling error only.
In a sample survey, the following question was asked: "Which of the following best represents your opinion on gun control? 1. The government should take away our guns. 2. We have the right to keep and bear arms. Identify the correct statement with reference to the survey question asked:
In a sample survey, the following question was asked: "Which of the following best represents your opinion on gun control?
1. The government should take away our guns.
2. We have the right to keep and bear arms.
Identify the correct statement with reference to the survey question asked:
A.
The question is slanted toward a desired response in favor of the second statement.
B.
The question is slanted toward a desired response in favor of the first statement.
C.
The question is not slanted toward a desired response.
Answer: A.
The question is slanted toward a desired response in favor of the second statement.
You want to investigate the attitudes of students at your school toward the school's policy on extra fees for lab courses. You have a grant that will pay the costs of contacting about 500 students. Assuming that budget is not a constraint, which of the following would be the most appropriate method of contacting the students?
You want to investigate the attitudes of students at your school toward the school's policy on extra fees for lab courses. You have a grant that will pay the costs of contacting about 500 students.
Assuming that budget is not a constraint, which of the following would be the most appropriate method of contacting the students?
A.
Mailed questionnaires
B.
Telephone interviews
C.
Face-to-face interviews
Answer: C.
Face-to-face interviews
The following question was asked in a sample survey: "In light of skyrocketing gasoline prices, we should consider opening up a very small amount of Alaskan wilderness for oil exploration as a way of reducing our dependence on foreign oil. Do you agree or disagree?
The following question was asked in a sample survey: "In light of skyrocketing gasoline prices, we should consider opening up a very small amount of Alaskan wilderness for oil exploration as a way of reducing our dependence on foreign oil. Do you agree or disagree?
A.
The question is slanted toward a desired response against the statement.
B.
The question is not slanted toward a desired response.
C.
The question is slanted toward a desired response in favor of the statement.
Answer: C.
The question is slanted toward a desired response in favor of the statement.
You want to investigate the attitudes of students at your school toward the school's policy on extra fees for lab courses. You have a grant that will pay the costs of contacting about 500 students. Which statement is true?
You want to investigate the attitudes of students at your school toward the school's policy on extra fees for lab courses. You have a grant that will pay the costs of contacting about 500 students.
Which statement is true?
A.
A stratified sample can be created by using student majors as strata.
B.
A cluster sample is impossible in this situation.
C.
A cluster sample could be obtained by selecting ten students at random from EACH major.
Answer: A.
A stratified sample can be created by using student majors as strata.
Which of the following do you think is the source of error that has been disregarded?
A survey of users of the Internet in 1995, when Internet use was much less common than now, found that males outnumbered females by nearly 2 to 1. This was a surprise because earlier surveys had put the ratio of men to women closer to 9 to 1. Later in the article we find this information: "Detailed surveys were sent to more than 13,000 organizations on the Internet; 1,468 usable responses were received. According to Mr. Quarterman, the margin of error is 2.8 percent, with a confidence level of 95 percent."
A.
Nonresponse
B.
Voluntary response
C.
Undercoverage
Answer: B.
Voluntary response
Which of the following do you think is the source of error that has been disregarded?
A.
Nonresponse
B.
Voluntary response
C.
Undercoverage
Answer: B.
Voluntary response
Which of the following statements correctly explains why we can't just say that 47% of all adult women do not get enough time for themselves?
A New York Times Poll on women's issues interviewed 1025 women randomly selected from the United States, excluding Alaska and Hawaii. The poll found that 47% of the women said they do not get enough time for themselves. The poll announced a margin of error of ±3 percentage points for 95% confidence in its conclusions.
A.
The result, that 47% women said they do not get enough time for themselves, is based on a sample that does not contain an equal proportion of the population from each state.
B.
The result, that 47% women said they do not get enough time for themselves, is based on a small sample size.
C.
The 47% of women who said they do not get enough time for themselves represents the proportion of the sample and not the proportion of the population.
Answer: C.
The 47% of women who said they do not get enough time for themselves represents the proportion of the sample and not the proportion of the population.
Which of the following statements correctly explains why we can't just say that 47% of all adult women do not get enough time for themselves?
A.
The result, that 47% women said they do not get enough time for themselves, is based on a sample that does not contain an equal proportion of the population from each state.
B.
The result, that 47% women said they do not get enough time for themselves, is based on a small sample size.
C.
The 47% of women who said they do not get enough time for themselves represents the proportion of the sample and not the proportion of the population.
Answer: C.
The 47% of women who said they do not get enough time for themselves represents the proportion of the sample and not the proportion of the population.
Which of the following statements is correct about the relation of margin of error for women and margin for error for men?
A New York Times Poll on women's issues interviewed 1025 women randomly selected from the United States, excluding Alaska and Hawaii. The poll also interviewed 472 randomly selected men. In conclusions about women, the poll announced a margin of error of ±3 percentage points for 95% confidence.
A.
The margin of error for men will be equal to the margin of error for women.
B.
The margin of error for men will be greater than margin of error for women.
C.
The margin of error for men will be smaller than the margin of error for women.
Answer: B.
The margin of error for men will be greater than margin of error for women.
Which of the following statements is correct about the relation of margin of error for women and margin for error for men?
A.
The margin of error for men will be equal to the margin of error for women.
B.
The margin of error for men will be greater than margin of error for women.
C.
The margin of error for men will be smaller than the margin of error for women.
Answer: B.
The margin of error for men will be greater than margin of error for women.
Which of the following statements correctly explains the result of the poll?
In February 2004, USA Today conducted an online poll. Visitors to their Web site were asked the following question: "Should the U.S. pass a constitutional amendment banning gay marriage?" Visitors could vote by clicking a button. The result as of 3:30 pm on February 25 was that 68.61% voted "No" and 31.39% voted "Yes." A total of 63,046 votes had been recorded. It was found that the margin of error for 95% confidence for a sample of this size is roughly equal to four-tenths of one percentage point.
A.
The margin of error is 0.4%. Therefore, it can be said with 95% confidence that 68.61%, plus or minus 0.4%, of American adults are opposed to having the United States pass a constitutional amendment banning gay marriage.
B.
68.61% is the correct value of population parameter p, representing the proportion of American adults who are opposed to have the United States pass a constitutional amendment banning gay marriage.
C.
The result of the poll is based on a voluntary response sample. Therefore, it cannot be said that 68.61%, plus or minus 0.4%, of American adults are opposed to having the United States pass a constitutional amendment banning gay marriage.
Answer: C.
The result of the poll is based on a voluntary response sample. Therefore, it cannot be said that 68.61%, plus or minus 0.4%, of American adults are opposed to having the United States pass a constitutional amendment banning gay marriage.
Which of the following statements correctly explains the result of the poll?
A.
The margin of error is 0.4%. Therefore, it can be said with 95% confidence that 68.61%, plus or minus 0.4%, of American adults are opposed to having the United States pass a constitutional amendment banning gay marriage.
B.
68.61% is the correct value of population parameter p, representing the proportion of American adults who are opposed to have the United States pass a constitutional amendment banning gay marriage.
C.
The result of the poll is based on a voluntary response sample. Therefore, it cannot be said that 68.61%, plus or minus 0.4%, of American adults are opposed to having the United States pass a constitutional amendment banning gay marriage.
Answer: C.
The result of the poll is based on a voluntary response sample. Therefore, it cannot be said that 68.61%, plus or minus 0.4%, of American adults are opposed to having the United States pass a constitutional amendment banning gay marriage.
Which of the following statements correctly explains the phrase "margin of error plus or minus 3 percentage points?
In October 2007, the Gallup Poll asked a sample of 1010 adults, "Are you in favor of the death penalty for a person convicted of murder?" The proportion who said they were in favor was 69%.Gallup says that the margin of error for this poll is ±3 percentage points.
A.
The true value is within 3 percentage points of the result obtained in this poll.
B.
The results are based on a method that is 95% of the time within 3 percentage points of the true value.
C.
The result of the poll is different from the true value by more than 3 percentage points.
Answer: B.
The results are based on a method that is 95% of the time within 3 percentage points of the true value.
Which of the following statements correctly explains the phrase "margin of error plus or minus 3 percentage points?
A.
The true value is within 3 percentage points of the result obtained in this poll.
B.
The results are based on a method that is 95% of the time within 3 percentage points of the true value.
C.
The result of the poll is different from the true value by more than 3 percentage points.
Answer: B.
The results are based on a method that is 95% of the time within 3 percentage points of the true value.
Which of the following statements correctly explains the meaning of the term '95% confidence', in the confidence statement?
A New York Times Poll on women's issues interviewed 1025 women randomly selected from the United States, excluding Alaska and Hawaii. The poll found that 47% of the women said they do not get enough time for themselves. The poll announced a margin of error of ±3 percentage points for 95% confidence in its conclusions.The confidence statement, in relation to the given scenario, is: "We are 95% confident that between 44% and 50% of all women would say that they do not get enough time for themselves."
A.
The interval 44% to 50% is based on a procedure that produces a margin of error (of ±3) 95% of the time.
B.
The interval 44% to 50% is based on a procedure that includes a sample representing 95% of population.
C.
The interval 44% to 50% is based on a procedure that captures the true population value 95% of the time.
Answer: C.
The interval 44% to 50% is based on a procedure that captures the true population value 95% of the tim
Which of the following statements correctly explains the meaning of the term '95% confidence', in the confidence statement?
A.
The interval 44% to 50% is based on a procedure that produces a margin of error (of ±3) 95% of the time.
B.
The interval 44% to 50% is based on a procedure that includes a sample representing 95% of population.
C.
The interval 44% to 50% is based on a procedure that captures the true population value 95% of the time.
Answer: C.
The interval 44% to 50% is based on a procedure that captures the true population value 95% of the tim
In October 2007, the Gallup Poll asked a sample of 1010 adults, "Are you in favor of the death penalty for a person convicted of murder?" The proportion who said they were in favor was 69%. Gallup says that the margin of error for this poll is ±3 percentage points. Suppose you want a margin of error half as large as estimated by Gallup. How many people must you plan to interview?
In October 2007, the Gallup Poll asked a sample of 1010 adults, "Are you in favor of the death penalty for a person convicted of murder?" The proportion who said they were in favor was 69%. Gallup says that the margin of error for this poll is ±3 percentage points.
Suppose you want a margin of error half as large as estimated by Gallup. How many people must you plan to interview?
A.
4040
B.
505
C.
2020
Answer: A. 4040
A management student is planning a project on student attitudes toward part-time work while attending college. She develops a questionnaire and plans to ask 25 randomly selected students to fill it out. Her faculty adviser approves the questionnaire but suggests that the sample size should be increased to at least 100 students. Which of the following statements correctly identifies the relation between the margin of error for sample sizes of 100 and 25?
A management student is planning a project on student attitudes toward part-time work while attending college. She develops a questionnaire and plans to ask 25 randomly selected students to fill it out. Her faculty adviser approves the questionnaire but suggests that the sample size should be increased to at least 100 students.
Which of the following statements correctly identifies the relation between the margin of error for sample sizes of 100 and 25?
A.
The margin of error for a sample size of 100 will be approximately one-fourth of the margin of error for a sample size of 25.
B.
The margin of error for a sample size of 100 will be approximately double of the margin of error for a sample size of 25.
C.
The margin of error for a sample size of 100 will be approximately half of the margin of error for a sample size of 25.
Answer: C.
The margin of error for a sample size of 100 will be approximately half of the margin of error for a sample size of 25.
A New York Times Poll on women's issues interviewed 1025 women randomly selected from the United States, excluding Alaska and Hawaii. The poll found that 47% of the women said they do not get enough time for themselves. The poll announced a margin of error of ±3 percentage points for 95% confidence in its conclusions. Which of the following statements is the correct confidence statement, in relation to the scenario?
A New York Times Poll on women's issues interviewed 1025 women randomly selected from the United States, excluding Alaska and Hawaii. The poll found that 47% of the women said they do not get enough time for themselves. The poll announced a margin of error of ±3 percentage points for 95% confidence in its conclusions.
Which of the following statements is the correct confidence statement, in relation to the scenario?
A.
We are 95% confident that between 44% and 50% of all women would say that they do not get enough time for themselves.
B.
We are sure that between 44% and 50% of all women would say that they do not get enough time for themselves.
C.
We are 95% confident that 47% of all women would say that they do not get enough time for themselves.
Answer: A. We are 95% confident that between 44% and 50% of all women would say that they do not get enough time for themselves.
A November 2007 Gallup Poll of 1004 adults found that 572 are satisfied with the total cost they pay for their health care. The announced margin of error is ±3 percentage points. The announced confidence level is 95%. Which statement is true?
A November 2007 Gallup Poll of 1004 adults found that 572 are satisfied with the total cost they pay for their health care. The announced margin of error is ±3 percentage points. The announced confidence level is 95%. Which statement is true?
A.
The population parameter p is the proportion of the sample that is satisfied with the total cost they pay for their health care.
B.
The population parameter p is the proportion, of the total number of samples, which is within the limits of margin of error.
C.
The population parameter p is proportion of the population who is satisfied with the total cost they pay for their health care.
Answer: C.
The population parameter p is proportion of the population who is satisfied with the total cost they pay for their health care.
A management student is planning a project on student attitudes toward part-time work while attending college. She develops a questionnaire and plans to ask 25 randomly selected students to fill it out. Her faculty adviser approves the questionnaire but suggests that the sample size should be increased to at least 100 students. Which of the following statements correctly explains the advantage of the larger sample?
A management student is planning a project on student attitudes toward part-time work while attending college. She develops a questionnaire and plans to ask 25 randomly selected students to fill it out. Her faculty adviser approves the questionnaire but suggests that the sample size should be increased to at least 100 students.
Which of the following statements correctly explains the advantage of the larger sample?
A.
A larger sample size will give less biased results.
B.
A larger sample size will give low bias and low variability.
C.
A larger sample size will give less variable results.
Answer: C.
A larger sample size will give less variable results.
A November 2007 Gallup Poll of 1004 adults found that 572 are satisfied with the total cost they pay for their health care. The announced margin of error is ±3 percentage points. The announced confidence level is 95%. Which of the statements is a correct and complete confidence statement in this scenario?
A November 2007 Gallup Poll of 1004 adults found that 572 are satisfied with the total cost they pay for their health care. The announced margin of error is ±3 percentage points. The announced confidence level is 95%. Which of the statements is a correct and complete confidence statement in this scenario?
A.
We are 95% confident that p is between 54% and 60%.
B.
We are 95% confident that p is 57%.
C.
We are sure that p is between 54% and 60%.
Answer: A.
We are 95% confident that p is between 54% and 60%.
The BusinessWeek online poll is available at the BusinessWeek website. Visitors can simply click appropriate buttons to vote. In response to the question "Do you think Google is too powerful?" (March 27, 2007), 1336 said "Yes," 2051 said "No", and 335 said that they were not sure. What was the sample size for this poll?
The BusinessWeek online poll is available at the BusinessWeek website. Visitors can simply click appropriate buttons to vote. In response to the question "Do you think Google is too powerful?" (March 27, 2007), 1336 said "Yes," 2051 said "No", and 335 said that they were not sure.
What was the sample size for this poll?
A.
335
B.
3722
C.
3136
D.
2051
Answer: B.
3722
Which of the following statements is appropriate about the proportion of the population who favor one-way streets?
Highway planners decided to make a main street in West Lafayette, Indiana, a one-way street. The Lafayette Journal and Courier took a one-day poll by inviting readers to call a telephone number to record their comments. The next day, the paper reported: "Journal and Courier readers overwhelmingly prefer two-way traffic flow in West Lafayette's Village area to one-way streets. By nearly a 7-1 margin, callers to the newspaper's Express Yourself opinion line on Wednesday complained about the one-way streets that have been in place since May. Of the 98 comments received, all but 14 said no to one-way."
A.
The proportion of the population who favor one-way streets is probably equal to the proportion 14/98 in the sample.
B.
The proportion of the population who favor one-way streets is probably larger than the proportion 14/98 in the sample.
C.
The proportion of the population who favor one-way streets is probably smaller than the proportion 14/98 in the sample.
Answer: B.
The proportion of the population who favor one-way streets is probably larger than the proportion 14/98 in the sample.
Which of the following statements is appropriate about the proportion of the population who favor one-way streets?
A.
The proportion of the population who favor one-way streets is probably equal to the proportion 14/98 in the sample.
B.
The proportion of the population who favor one-way streets is probably larger than the proportion 14/98 in the sample.
C.
The proportion of the population who favor one-way streets is probably smaller than the proportion 14/98 in the sample.
Answer: B.
The proportion of the population who favor one-way streets is probably larger than the proportion 14/98 in the sample.
Choosing at random is a "fair" way to decide who gets some scarce good, in the sense that everyone has the same chance to win. However, random choice isn't always a good idea. At times we don't want to treat everyone at the same because some people have a better claim. In which of the following situations, would you not prefer to choose at random?
Choosing at random is a "fair" way to decide who gets some scarce good, in the sense that everyone has the same chance to win. However, random choice isn't always a good idea. At times we don't want to treat everyone at the same because some people have a better claim.
In which of the following situations, would you not prefer to choose at random?
A.
The basketball arena has 4000 student seats, and 7000 students want tickets.
B.
Young men chosen for army service, during the Vietnam War.
C.
The list of people waiting for liver transplants is larger than the number of livers available.
Answer: C.
The list of people waiting for liver transplants is larger than the number of livers available.
To assess how its teaching assistants are performing, the statistics department at a large university randomly selects three of its teaching assistants each week and sends a faculty member to visit their classes. The current list of 20 teaching assistants is given below.
To assess how its teaching assistants are performing, the statistics department at a large university randomly selects three of its teaching assistants each week and sends a faculty member to visit their classes. The current list of 20 teaching assistants is given below.
01. Bautista 06. Frazier 11. Miller 16. Walters02. Bolen 07. Kumar 12. Podboy 17. Wang
03. Clottey 08. Lam 13. Roy 18. Weimer
04. Counts 09. Lovesky 14. Schumacher 19. Yu
05. Draper 10. Marin 15. Tower 20. Zhang
The department examines the first 13 two-digit groups in line 116 of Table A. Line 116 is:
14459 26056 31424 80371 65103 62253 50490 61181.
The first 13 two-digits groups are: 14, 45, 92, 60, 56, 31, 42, 48, 03, 71, 65, 10, and 36.
Which of the following teaching assistants would the sample consist of?
A.
Clottey, Marin, and Schumacher
B.
Draper, Marin, and Schumacher
C.
Bautista, Counts, and Draper
D.
Schumacher, Counts, and Draper
Answer: A.
Clottey, Marin, and Schumacher
In 2005 the San Francisco Bay Times reported on a poll in New Zealand that found that New Zealanders opposed the nation's new gay-inclusive civil-unions law by a 3-1 ratio. This poll was a call-in poll that cost $1 to participate in. The San Francisco Bay Times article also reported that a scientific polling organization found that New Zealanders favor the law by a margin of 56.4% to 39.3%. Which of the following statements is correct about the reliability of the polls?
In 2005 the San Francisco Bay Times reported on a poll in New Zealand that found that New Zealanders opposed the nation's new gay-inclusive civil-unions law by a 3-1 ratio. This poll was a call-in poll that cost $1 to participate in. The San Francisco Bay Times article also reported that a scientific polling organization found that New Zealanders favor the law by a margin of 56.4% to 39.3%.
Which of the following statements is correct about the reliability of the polls?
A.
The polling result of neither call-in poll nor the scientific polling organization can be considered reliable as there is so much difference in the results of two polls.
B.
The scientific polling organization may not have produced the reliable result and therefore causing its results to differ so much with the result of the call-in poll.
C.
The call-in poll used the Voluntary Response method, so their poll results cannot be considered reliable.
Answer: C.
The call-in poll used the Voluntary Response method, so their poll results cannot be considered reliable.
A college wants to gather student opinion about parking for students on campus. It isn't practical to contact all students. Which of the following is an example of a good way to choose a sample?
A college wants to gather student opinion about parking for students on campus. It isn't practical to contact all students.
Which of the following is an example of a good way to choose a sample?
A.
Selection of random 50 students and interviewing them
B.
A survey form published in the campus newspaper
C.
Interviewing students when they leave the parking at the campus
Answer: B.
A survey form published in the campus newspaper
The BusinessWeek online poll is available at the BusinessWeek website. Visitors can simply click appropriate buttons to vote. In response to the question "Do you think Google is too powerful?" (March 27, 2007), 1336 said "Yes," 2051 said "No", and 335 said that they were not sure. Above the poll question, the following statement was mentioned: "Google's accelerating lead in search and its moves into software and traditional advertising are sparking a backlash among rivals." How might this statement affect the polls?
The BusinessWeek online poll is available at the BusinessWeek website. Visitors can simply click appropriate buttons to vote. In response to the question "Do you think Google is too powerful?" (March 27, 2007), 1336 said "Yes," 2051 said "No", and 335 said that they were not sure.
Above the poll question, the following statement was mentioned: "Google's accelerating lead in search and its moves into software and traditional advertising are sparking a backlash among rivals." How might this statement affect the polls?
A.
The statement would have increased the sample size.
B.
The statement would have made the poll biased.
C.
The statement would have made the poll reliable.
Answer: B.
The statement would have made the poll biased
A university has 30,000 undergraduate and 10,000 graduate students. A survey of student opinion concerning health care benefits for domestic partners of students selects 300 of the 30,000 undergraduate students at random and then separately selects 100 of the 10,000 graduate students at random. The 400 students chosen make up the sample. Which of the following statements correctly explains why this sampling method gives each student an equal chance to be chosen?
A university has 30,000 undergraduate and 10,000 graduate students. A survey of student opinion concerning health care benefits for domestic partners of students selects 300 of the 30,000 undergraduate students at random and then separately selects 100 of the 10,000 graduate students at random. The 400 students chosen make up the sample.
Which of the following statements correctly explains why this sampling method gives each student an equal chance to be chosen?
A. Every undergraduate student has a 75% chance of being selected and every graduate student has a 25% chance of being selected, which is proportional to the makeup of the student body.
B. Any student has a 50% chance of being chosen, since the student is either selected or not.
C. Any student, undergraduate or graduate, has a 1 in 100 chance of being selected.
Answer: C. Any student, undergraduate or graduate, has a 1 in 100 chance of being selected.
A national survey of TV network news viewers found that 48% said they would believe a phone-in poll of 300,000 persons rather than a random sample of 1000 persons. Of the viewers, 42% said they would believe the random sample poll. Which of the following statements correctly explains why the opinions of only 1000 randomly chosen respondents are a better guide to what all people think than the opinions of 300,000 callers?
A national survey of TV network news viewers found that 48% said they would believe a phone-in poll of 300,000 persons rather than a random sample of 1000 persons. Of the viewers, 42% said they would believe the random sample poll.
Which of the following statements correctly explains why the opinions of only 1000 randomly chosen respondents are a better guide to what all people think than the opinions of 300,000 callers?
A.
The 1000 randomly chosen respondents represent the population as a whole, whereas the 300,000 callers did not do so.
B.
The 1000 randomly chosen individuals were chosen as a personal choice of the TV network, whereas the 300,000 called voluntarily and do not represent the choice of the TV network.
C.
The 1000 randomly chosen respondents represent the intellectual population, whereas the 300,000 callers did not do so
Answer: B.
The 1000 randomly chosen individuals were chosen as a personal choice of the TV network, whereas the 300,000 called voluntarily and do not represent the choice of the TV network.
Highway planners decided to make a main street in West Lafayette, Indiana, a one-way street. The Lafayette Journal and Courier took a one-day poll by inviting readers to call a telephone number to record their comments. The next day, the paper reported: "Journal and Courier readers overwhelmingly prefer two-way traffic flow in West Lafayette's Village area to one-way streets. By nearly a 7-1 margin, callers to the newspaper's Express Yourself opinion line on Wednesday complained about the one-way streets that have been in place since May. Of the 98 comments received, all but 14 said no to one-way." What population do you think the newspaper wants information about?
Highway planners decided to make a main street in West Lafayette, Indiana, a one-way street. The Lafayette Journal and Courier took a one-day poll by inviting readers to call a telephone number to record their comments. The next day, the paper reported: "Journal and Courier readers overwhelmingly prefer two-way traffic flow in West Lafayette's Village area to one-way streets. By nearly a 7-1 margin, callers to the newspaper's Express Yourself opinion line on Wednesday complained about the one-way streets that have been in place since May. Of the 98 comments received, all but 14 said no to one-way."
What population do you think the newspaper wants information about?
A.
Highway planners
B.
Residents of West Lafayette (and Lafayette)
C.
All readers of Lafayette Journal and Courier
Answer: B.
Residents of West Lafayette (and Lafayette)
As part of a project for a political science class, a student decided to conduct an online poll. The student asked the following question: "Do you think that illegal immigrants should be allowed to pay instate tuition, even though they are not legal citizens of that state?" Possible responses were Yes, No, and Unsure. Of those who responded, 81% said No, 19% said Yes, and 0% said Unsure. Which of the following statements correctly explains the result of the poll with respect to reliability and bias?
As part of a project for a political science class, a student decided to conduct an online poll. The student asked the following question: "Do you think that illegal immigrants should be allowed to pay instate tuition, even though they are not legal citizens of that state?" Possible responses were Yes, No, and Unsure. Of those who responded, 81% said No, 19% said Yes, and 0% said Unsure.
Which of the following statements correctly explains the result of the poll with respect to reliability and bias?
A.
The result of the poll is biased because it is based on voluntary response method.
B.
The result of the poll is not reliable because it is based on convenience sample method.
C.
The result of the poll can be considered reliable and unbiased.
Answer: A.
The result of the poll is biased because it is based on voluntary response method.
The BusinessWeek online poll is available at the BusinessWeek website. Visitors can simply click appropriate buttons to vote. In response to the question "Do you think Google is too powerful?" (March 27, 2007), 1336 said "Yes," 2051 said "No", and 335 said that they were not sure. Why do you think the poll may give unreliable information?
The BusinessWeek online poll is available at the BusinessWeek website. Visitors can simply click appropriate buttons to vote. In response to the question "Do you think Google is too powerful?" (March 27, 2007), 1336 said "Yes," 2051 said "No", and 335 said that they were not sure.
Why do you think the poll may give unreliable information?
A.
Business Week uses convenience sampling.
B.
Online polls may not be reliable.
C.
Sample size is small.
Answer: A.
Business Week uses convenience sampling.
The Gallup Poll is an example of a:
The Gallup Poll is an example of a:
A.
Population
B.
Census
C.
Experiment
D.
Sample Survey
Answer: D. Sample Survey
A local newspaper in the State of Connecticut conducts a poll on whether the people of the state believe the "No Child Left Behind" law is effective. The newspaper contacts 1000 subscribers. The population of this poll is:
A local newspaper in the State of Connecticut conducts a poll on whether the people of the state believe the "No Child Left Behind" law is effective. The newspaper contacts 1000 subscribers. The population of this poll is:
A.
Those who favor or disapprove of the "No Child Left Behind" law
B.
People who live in the State of Connecticut
C.
Those who are affected by "No Child Left Behind"
D.
The 1000 people surveyed
Answer: B.
People who live in the State of Connecticut
Brian gathers data from his classmates about the computers they own: What are the individuals in this data set?
Brian gathers data from his classmates about the computers they own:
What are the individuals in this data set?
A.
The year purchased
B.
Brian's classmates
C.
The amount of memory
D.
The type of operating system
Answer: B.
Brian's classmates
The difference between an experiment and an observational study is:
The difference between an experiment and an observational study is:
A.
An observational study tries to gather information without interfering; an experiment looks to actively impose a treatment to see how they respond.
B.
An experiment tries not to change behavior, an observational study does.
C.
An experiment deliberately imposes a treatment whereas an observational study measures the unintentional effects of the treatment as a result of the observation being done.
Answer: A.
An observational study tries to gather information without interfering; an experiment looks to actively impose a treatment to see how they respond.
The Nielsen television ratings is an example of a:
The Nielsen television ratings is an example of a:
A.
Experiment
B.
Population
C.
Census
D.
Sample Survey
Answer: D. Sample Survey
Which of the following situations is an example of an experiment?
Consider the three situations:
I. You ask a sample of doctors about the health risks involved with going out in the cold without a jacket.
II. On cold days, you record which of your classmates come to school without a jacket. Later, you record how many of those students become sick. You take notes and observe at a local gym your fellow members who go outside with a wet head and notice if they are sick when they return to the gym at a later date.
III. You find 30 adults and divide them into two groups. The first group is told not to wear jackets on cold days, the other group is told to wear jackets on cold days.You then compare the number from each group who get sick after a string of cold days.
A.
Situation III
B.
Situation I
C.
Situation II
Answer: A. Situation III
I. You ask a sample of doctors about the health risks involved with going out in the cold without a jacket.
II. On cold days, you record which of your classmates come to school without a jacket. Later, you record how many of those students become sick. You take notes and observe at a local gym your fellow members who go outside with a wet head and notice if they are sick when they return to the gym at a later date.
III. You find 30 adults and divide them into two groups. The first group is told not to wear jackets on cold days, the other group is told to wear jackets on cold days.You then compare the number from each group who get sick after a string of cold days.
Which of the following situations is an example of an experiment?
A.
Situation III
B.
Situation I
C.
Situation II
Answer: A. Situation III
Which of the following situations is an example of an observational study?
Consider the three situations:
I. You ask a sample of doctors about the health risks involved with going out in the cold without a jacket.
II. On cold days, you record which of your classmates come to school without a jacket. Later, you record how many of those students become sick. You take notes and observe at a local gym your fellow members who go outside with a wet head and notice if they are sick when they return to the gym at a later date.
III. You find 30 adults and divide them into two groups. The first group is told not to wear jackets on cold days, the other group is told to wear jackets on cold days.You then compare the number from each group who get sick after a string of cold days.
A.
Situation II
B.
Situation I
C.
Situation III
Answer: A. Situation II
I. You ask a sample of doctors about the health risks involved with going out in the cold without a jacket.
II. On cold days, you record which of your classmates come to school without a jacket. Later, you record how many of those students become sick. You take notes and observe at a local gym your fellow members who go outside with a wet head and notice if they are sick when they return to the gym at a later date.
III. You find 30 adults and divide them into two groups. The first group is told not to wear jackets on cold days, the other group is told to wear jackets on cold days.You then compare the number from each group who get sick after a string of cold days.
Which of the following situations is an example of an observational study?
A.
Situation II
B.
Situation I
C.
Situation III
Answer: A. Situation II
What is the difference between a census and a sample survey?
What is the difference between a census and a sample survey?
A.A census attempts to include the entire population in the survey whereas a sample survey only studies some of the members of the population.
B.
A census looks at a larger group than a sample survey to gather information about the population.
C.
A census can study many variables whereas a sample survey can only study one or two.
D.
A census can only be conducted by a government whereas a sample survey can be conducted by anyone.
Answer: B. A census looks at a larger group than a sample survey to gather information about the population.
Which of the variables is not considered to be numerical?
Which of the variables is not considered to be numerical?
A.
The type of operating system
B.
The year purchased
C.
the number of Brian's classmates
D.
The amount of memory
Answer: A. Type of operating system
The presidential election campaign is in full swing, and the candidates have hired polling organizations to take regular polls to find out what the voters think about the issues. What does the standard of informed consent require the polling organizations to tell potential respondents?
The presidential election campaign is in full swing, and the candidates have hired polling organizations to take regular polls to find out what the voters think about the issues. What does the standard of informed consent require the polling organizations to tell potential respondents?
(A) The achievements of the candidate or the political party
(B) Which candidate the pollster personally supports and why
(C) The election process and date of election
(D) The kind of questions they will be asked and the approximate amount of time required to complete the survey
Answer: (D) The kind of questions they will be asked and the approximate amount of time required to complete the survey
A local newspaper in the State of Connecticut conducts a poll on whether the people of the state believe the "No Child Left Behind" law is effective. The newspaper contacts 1000 subscribers. The population of this poll is:
A local newspaper in the State of Connecticut conducts a poll on whether the people of the state believe the "No Child Left Behind" law is effective. The newspaper contacts 1000 subscribers. The population of this poll is:
(A) The 1000 people surveyed
(B) Those who favor or disapprove of the "No Child Left Behind" law
(C) People who live in the State of Connecticut
(D) Those who are affected by "No Child Left Behind"
Answer: (C) People who live in the State of Connecticut
The sampling variability of a statistic reflects
The sampling variability of a statistic reflects
(A) the difference in the value of a statistic across repeated samples
(B) the error due to a voluntary response sample
(C) the difference in responses with a single sample
(D) the difference between the statistic and the true parameter
Answer: (A) the difference in the value of a statistic across repeated samples
A manufacturer of chisels is interested in determining how the angle at which the cutting edge is sharpened affects tool abrasion. To answer this question, engineers obtain 20 similar chisels. They sharpen five chisels at each of 22.5, 25, 27.5, and 30 degrees. Then, they measure the amount of abrasion (rated on a scale of 1 to 10, with 10 being the worst) after cutting several mortises (square holes) in 3/4-inch hard maple boards. Which of the following is the explanatory variable in the given study?
A manufacturer of chisels is interested in determining how the angle at which the cutting edge is sharpened affects tool abrasion. To answer this question, engineers obtain 20 similar chisels. They sharpen five chisels at each of 22.5, 25, 27.5, and 30 degrees. Then, they measure the amount of abrasion (rated on a scale of 1 to 10, with 10 being the worst) after cutting several mortises (square holes) in 3/4-inch hard maple boards. Which of the following is the explanatory variable in the given study?
(A) Mortises
(B) Tool abrasion
(C) Angle of cutting edge
(D) Sharpening of chisels
Answer: (C) Angle of cutting edge
In a sample survey, the following question was asked: "Which of the following best represents your opinion on gun control?
In a sample survey, the following question was asked: "Which of the following best represents your opinion on gun control?
1. The government should take away our guns.
2. We have the right to keep and bear arms.
Identify the correct statement with reference to the survey question asked:
(A) The question is slanted toward a desired response in favor of the first statement.
(B) The question is slanted toward a desired response in favor of the second statement.
(C) The question is not slanted toward a desired response.
(D) None of the above are true.
Answer: (B) The question is slanted toward a desired response in favor of the second statement.
A New York Times Poll on women's issues interviewed 1025 women randomly selected from the United States, excluding Alaska and Hawaii. The poll found that 47% of the women said they do not get enough time for themselves. The poll announced a margin of error of ±3 percentage points for 95% confidence in its conclusions. The confidence statement, in relation to the given scenario, is: "We are 95% confident that between 44% and 50% of all women would say that they do not get enough time for themselves." Which of the following statements correctly explains the meaning of the term '95% confidence', in the confidence statement?
A New York Times Poll on women's issues interviewed 1025 women randomly selected from the United States, excluding Alaska and Hawaii. The poll found that 47% of the women said they do not get enough time for themselves. The poll announced a margin of error of ±3 percentage points for 95% confidence in its conclusions. The confidence statement, in relation to the given scenario, is: "We are 95% confident that between 44% and 50% of all women would say that they do not get enough time for themselves." Which of the following statements correctly explains the meaning of the term '95% confidence', in the confidence statement?
(A) The interval 44% to 50% is based on a procedure that produces a margin of error (of ±3) 95% of the time.
(B) The interval 44% to 50% is based on a procedure that includes a sample representing 95% of population.
(C) The interval 44% to 50% is based on a sample that we are 95% confident is a simple random sample.
(D) The interval 44% to 50% is based on a procedure that captures the true population value 95% of the time.
Answer: (D) The interval 44% to 50% is based on a procedure that captures the true population value 95% of the time.
A national survey of TV network news viewers found that 48% said they would believe a phone-in poll of 300,000 persons rather than a random sample of 1000 persons. Of the viewers, 42% said they would believe the random sample poll. Which of the following statements correctly explains why the opinions of only 1000 randomly chosen respondents are a better guide to what all people think than the opinions of 300,000 callers?
A national survey of TV network news viewers found that 48% said they would believe a phone-in poll of 300,000 persons rather than a random sample of 1000 persons. Of the viewers, 42% said they would believe the random sample poll. Which of the following statements correctly explains why the opinions of only 1000 randomly chosen respondents are a better guide to what all people think than the opinions of 300,000 callers?
(A) The 1000 randomly chosen respondents represent the intellectual population, whereas the 300,000 callers did not do so.
(B) The 1000 respondents were especially chosen because they are attentive TV viewers.
(C) The 1000 randomly chosen individuals were chosen as a personal choice of the TV network, whereas the 300,000 called voluntarily and do not represent the choice of the TV network.
(D) The 1000 randomly chosen respondents represent the population as a whole, whereas the 300,000 callers did not do so.
Answer: (D) The 1000 randomly chosen respondents represent the population as a whole, whereas the 300,000 callers did not do so.
Studies have suggested that compounds in broccoli might combat the effects of overexposure to ultraviolet radiation. We conduct an experiment to determine whether a cream consisting of a broccoli extract reduces sunburn pain. Sixty patients suffering from pain from severe sunburn are available. What is a good way to conduct the experiment?
Studies have suggested that compounds in broccoli might combat the effects of overexposure to ultraviolet radiation. We conduct an experiment to determine whether a cream consisting of a broccoli extract reduces sunburn pain. Sixty patients suffering from pain from severe sunburn are available. What is a good way to conduct the experiment?
(A) Give the cream to all 60 patients, and record their responses.
(B) Allow the patients to choose either the cream or an over-the-counter alternative, and record the responses.
(C) Divide the patients randomly into three groups of 20 patients each. Give one group the cream, another group an over-the-counter sunburn relief product, and the last group a placebo. Record the responses.
(D) Give some patients the cream and others the placebo, being sure to inform the patients which treatment they are receiving. Record the responses.
Answer: (C) Divide the patients randomly into three groups of 20 patients each. Give one group the cream, another group an over-the-counter sunburn relief product, and the last group a placebo. Record the responses.
Informed consent can be tricky to obtain when the subjects are
Informed consent can be tricky to obtain when the subjects are
(A) agricultural plots
(B) industrial parts
(C) volunteers
(D) children
Answer: (D) children
Taking a larger sample size will reduce what about a resulting statistic?
Taking a larger sample size will reduce what about a resulting statistic?
(A) bias
(B) sampling variability
(C) accuracy
(D) computational difficulty
Answer: (B) sampling variability
For which type of sample can a reliable margin of error be derived?
For which type of sample can a reliable margin of error be derived?
(A) convenience sample
(B) simple random sample
(C) census
(D) voluntary response sample
Answer: (B) simple random sample
A researcher observes the body-mass index (BMI), the number of school meals eaten, and the sex for a sample of schoolchildren. The goal of the study is to determine the relationship between BMI and number of school meals, and whether this relationship depends on the child's sex. What type of study is this?
A researcher observes the body-mass index (BMI), the number of school meals eaten, and the sex for a sample of schoolchildren. The goal of the study is to determine the relationship between BMI and number of school meals, and whether this relationship depends on the child's sex. What type of study is this?
(A) Observational, since the children are regularly watched
(B) Experiment, since there are human subjects in the study
(C) Experiment, since we seek to investigate a cause-effect relationship
(D) Observational, since the researcher imposes no treatment on the children
Answer: (D) Observational, since the researcher imposes no treatment on the children
A researcher observes the body-mass index (BMI), the number of school meals eaten, and the sex for a sample of schoolchildren. What are the individuals in the data set?
A researcher observes the body-mass index (BMI), the number of school meals eaten, and the sex for a sample of schoolchildren. What are the individuals in the data set?
(A) Schoolchildren and the researcher
(B) Schoolchildren
(C) BMI, number of school meals, and sex
(D) researcher and sex
Answer: c) School Children
A researcher observes the body-mass index (BMI), the number of school meals eaten, and the sex for a sample of schoolchildren. What are the variables in the data set?
A researcher observes the body-mass index (BMI), the number of school meals eaten, and the sex for a sample of schoolchildren. What are the variables in the data set?
(A) Schoolchildren and the researcher
(B) Schoolchildren, BMI, and number of school meals
(C) BMI, number of school meals, and sex
(D) only BMI
Answer: (C) BMI, number of school meals, and sex
If a survey suffers from a high nonresponse rate, what is a possible remedy?
If a survey suffers from a high nonresponse rate, what is a possible remedy?
(A) Using, as our data, the responses that we think nonrespondents would have given
(B) Weighting the responses of underrepresented groups more heavily
(C) Using a matched pairs design instead
(D) Increasing the standard deviation of the sample
Answer: (B) Weighting the responses of underrepresented groups more heavily
An example of a response error is a sample survey is when
An example of a response error is a sample survey is when
(A) the respondent's answer is incorrectly recorded by the researcher.
(B) the respondent cannot be reached for the survey.
(C) the respondent refuses to participate in the survey.
(D) the respondent incorrectly reports her annual income.
Answer: (D) the respondent incorrectly reports her annual income.
What is an ethical problem with placebo-controlled studies?
What is an ethical problem with placebo-controlled studies?
(A) Patients who could benefit from the experimental treatment may be selected for the placebo treatment.
(B) Placebo treatments do not effectively control for the "placebo effect" when the subject does not know which treatment he is receiving.
(C) With a placebo-controlled study, a randomized comparative experiment is impossible.
(D) It is logistically impossible to give some patients a placebo.
Answer: (A) Patients who could benefit from the experimental treatment may be selected for the placebo treatment.
In the Tuskegee Syphilis Study, the researchers
In the Tuskegee Syphilis Study, the researchers
(A) relied on a sample survey with leading questions.
(B) used a cluster sample.
(C) unethically put the scientific goal ahead of the subjects' well-being.
(D) did not have a sufficient sample size.
Answer: (C) unethically put the scientific goal ahead of the subjects' well-being.
What is the purpose of an institutional review board?
What is the purpose of an institutional review board?
(A) To review the institutions at which research is conducted.
(B) To pick the principal investigator of a research study.
(C) To decide whether the study should receive federal funding, based on the quality of the proposed research.
(D) To ensure that research proposals treat human subjects ethically and inform subjects about the study and any risks.
Answer: (D) To ensure that research proposals treat human subjects ethically and inform subjects about the study and any risks.
Suppose in a study of federal tax revenues, a sample of citizens' taxable incomes for 2014 is collected. The researchers intend to summarize the data for each state, but keep individuals' data private. This study is
Suppose in a study of federal tax revenues, a sample of citizens' taxable incomes for 2014 is collected. The researchers intend to summarize the data for each state, but keep individuals' data private. This study is
(A) confidential
(B) experimental
(C) anonymous
(D) exponential
Answer: (A) confidential
Suppose an experiment has two explanatory variables. The first explanatory variable has 2 possible values and the second explanatory variable has 4 possible values. How many treatments are there in the experiment?
Suppose an experiment has two explanatory variables. The first explanatory variable has 2 possible values and the second explanatory variable has 4 possible values. How many treatments are there in the experiment?
(A) 4
(B) 6
(C) 8
(D) 16
Answer: (C) 8
In a weight-loss study, 10% of the subjects getting the experimental drug dropped out before the finish and 58% of the subjects getting the placebo dropped out. It is speculated that subjects in a weight-loss experiment may prematurely drop out when they find themselves not losing weight. This is an example of:
In a weight-loss study, 10% of the subjects getting the experimental drug dropped out before the finish and 58% of the subjects getting the placebo dropped out. It is speculated that subjects in a weight-loss experiment may prematurely drop out when they find themselves not losing weight. This is an example of:
(A) Nonadherence, but it does not bias the study results
(B) Dropout that does bias the study results
(C) Dropout, but it does not bias the study results
(D) Nonadherence that does bias the study results
Answer: (B) Dropout that does bias the study results
Suppose subjects in an experiment are initially separated into age groups. Then, within each age group, subjects are randomly assigned to one of 4 different treatments. This is a:
Suppose subjects in an experiment are initially separated into age groups. Then, within each age group, subjects are randomly assigned to one of 4 different treatments. This is a:
(A) block design
(B) matched pairs design
(C) completely randomized design
(D) systematic design
Answer: (A) block design
Which is NOT one of the three major principles of experimental design?
Which is NOT one of the three major principles of experimental design?
(A) classification
(B) replication
(C) control
(D) randomization
Answer: (A) classification
In a sample of professors on a university campus, the researcher randomly selects 5 academic departments, and then interviews each professor in those selected departments. What type of sampling scheme is this?
In a sample of professors on a university campus, the researcher randomly selects 5 academic departments, and then interviews each professor in those selected departments. What type of sampling scheme is this?
(A) convenience sample
(B) cluster sample
(C) stratified random sample
(D) simple random sample
Answer: (B) cluster sample
Stemplots are mostly useful for displaying
Stemplots are mostly useful for displaying
(A) categorical data sets that are relatively small.
(B) numerical data sets that are relatively small.
(C) categorical data sets that are very large.
(D) numerical data sets that are very large.
Answer: (B) numerical data sets that are relatively small.
Which variable's distribution would be conveniently represented by a pie chart?
Which variable's distribution would be conveniently represented by a pie chart?
(A) lengths of wild newts
(B) weights of football players
(C) alcohol percentages of beers
(D) final letter grades of STAT 110 students
Answer: (D) final letter grades of STAT 110 students
If students who attend class regularly tend to have better final grades than students who miss class often, then class attendance, as a measure of student success, has
If students who attend class regularly tend to have better final grades than students who miss class often, then class attendance, as a measure of student success, has
(A) good validity
(B) high bias
(C) good predictive validity
(D) high reliability
Answer: (C) good predictive validity
Suppose that you and your friends emptied your pockets of coins and recorded the year marked on each coin. The distribution is left-skewed. Identify the most obvious reason for a left-skewed distribution.
Suppose that you and your friends emptied your pockets of coins and recorded the year marked on each coin. The distribution is left-skewed. Identify the most obvious reason for a left-skewed distribution.
(A) The number of older and newer coins is the same.
(B) Pennies are the most common type of coin.
(C) Older coins are more in number.
(D) Newer coins are more common than older coins.
Answer: (D) Newer coins are more common than older coins.
Refer to the histogram that shows the salaries of the players of the New York Yankees baseball team as of the opening day of the 2007 season. Identify the shape of the distribution.
Refer to the histogram that shows the salaries of the players of the New York Yankees baseball team as of the opening day of the 2007 season. Identify the shape of the distribution.
(A) skewed to the right
(B) bell-shaped
(C) skewed to the left
(D) symmetric
Answer: (C) skewed to the right
What is the best way for an academic department to measure student dissatisfaction with its course instructors?
What is the best way for an academic department to measure student dissatisfaction with its course instructors?
(A) Number of negative ratings on ratemyprofessor.com
(B) Proportion of below-satisfactory ratings on end-of-semester evaluations by students
(C) Number of below-satisfactory ratings on end-of-semester evaluations by students
(D) Number of students signed up for the course
Answer: (B) Proportion of below-satisfactory ratings on end-of-semester evaluations by students
Consider an easy exam in which most of the students get scores between 90 and the maximum score of 100. A few get scores between 80 and 90, and even fewer get scores between 70 and 80, and just a couple get scores below 70. The histogram of scores on this exam would show a distribution that is
Consider an easy exam in which most of the students get scores between 90 and the maximum score of 100. A few get scores between 80 and 90, and even fewer get scores between 70 and 80, and just a couple get scores below 70. The histogram of scores on this exam would show a distribution that is
(A) symmetric
(B) skewed to the left
(C) bimodal
(D) skewed to the right
Answer: (D) skewed to the Left
A researcher observes the weight, the height, the number of school meals eaten, and the sex for a sample of schoolchildren. Which variables are numerical and which are categorical?
A researcher observes the weight, the height, the number of school meals eaten, and the sex for a sample of schoolchildren. Which variables are numerical and which are categorical?
(A) Numerical: sex, weight, height. Categorical: school meals eaten
(B) Numerical: school meals eaten. Categorical: sex, weight, height.
(C) Numerical: weight, height. Categorical: school meals eaten, sex
(D) Numerical: school meals eaten, weight, height. Categorical: sex
Answer: (D) Numerical: school meals eaten, weight, height. Categorical: sex
What is the best approach in data analysis when we initially detect an outlier?
What is the best approach in data analysis when we initially detect an outlier?
(A) Assume the outlying data is due to a recording error.
(B) Do nothing, since the outlier is only a small part of the data set.
(C) Remove the outlier from the data set summarily.
(D) Go back and further investigate that particular observation
Answer: (D) Go back and further investigate that particular observation
The distribution of a variable tells us
The distribution of a variable tells us
(A) which values the variable takes
(B) how often the variables takes the different values
(C) Both of the above
(D) Neither of the above
Answer: (C) Both of the above
The following graph appeared in the Lexington (Ky.) Herald-Leader in October 5, 1975. Identify the reason why this graph is an incorrect representation of data.
The following graph appeared in the Lexington (Ky.) Herald-Leader in October 5, 1975. Identify the reason why this graph is an incorrect representation of data.
(A) The value of a currency cannot be plotted on a graph.
(B) The time scale on the horizontal axis is erratic.
(C) Pounds and dollars are not comparable units.
(D) The vertical axis should display British pounds.
Answer: (B) The time scale on the horizontal axis is erratic.
Consider the following numerical data set: 23, 31, 34, 37, 39, 42, 45, 45. What is the sample median?
Consider the following numerical data set: 23, 31, 34, 37, 39, 42, 45, 45. What is the sample median?
(A) 37
(B) 38
(C) 39
(D) 45
Answer: (B) 38
What can be determined from a frequency histogram but not a relative frequency histogram?
What can be determined from a frequency histogram but not a relative frequency histogram?
(A) The overall sample size
(B) The shape of the distribution
(C) The center of the distribution
(D) The skewness of the distribution
Answer: (A) The overall sample size
Refer to the histogram of the number of minority students, black, Hispanic, Native American, who earned doctorate degrees in engineering from 152 universities during 2000 to 2002. The classes for the histogram are 1-5, 6-10, and so on. Even without the actual data, you can use the position of the values of the five-number summary and the histogram to give the five-number summary approximately. About how many minority engineering PhD's must a university graduate to be in the top quarter?
Refer to the histogram of the number of minority students, black, Hispanic, Native American, who earned doctorate degrees in engineering from 152 universities during 2000 to 2002. The classes for the histogram are 1-5, 6-10, and so on. Even without the actual data, you can use the position of the values of the five-number summary and the histogram to give the five-number summary approximately. About how many minority engineering PhD's must a university graduate to be in the top quarter?
(A) 2
(B) 4
(C) 6
(D) 8
Answer: (D) 8
Consumers are turning to trucks, SUVs, and minivans in place of passenger cars. The following is the data on sales of new cars and trucks in the United States (The definition of "truck" includes SUVs and minivans). Two line graphs are plotted on the same axes to compare the change in car and truck sales over time. Car sales are shown with the solid line graph and truck sales are shown with the dashed line graph. Which of the following statements correctly describes the trend displayed by the graph?
Consumers are turning to trucks, SUVs, and minivans in place of passenger cars. The following is the data on sales of new cars and trucks in the United States (The definition of "truck" includes SUVs and minivans). Two line graphs are plotted on the same axes to compare the change in car and truck sales over time. Car sales are shown with the solid line graph and truck sales are shown with the dashed line graph. Which of the following statements correctly describes the trend displayed by the graph?
(A) Before 1999, the number of cars was greater than the number of trucks.
(B) The number of cars sold shows an overall increasing trend.
(C) Before 1999, the number of trucks was greater than the number of cars.
(D) Before 1999, the numbers of cars and trucks were equal.
Answer: (A) Before 1999, the number of cars was greater than the number of trucks.
Which is the most valid measurement of maximum running speed for an athlete?
Which is the most valid measurement of maximum running speed for an athlete?
(A) time in a 10-mile race
(B) highest amount of weight lifted by one leg
(C) time in a 40-yard dash
(D) number of sit-ups done in one minute
Answer: (C) time in a 40-yard dash
Approximately what percentage of a data set is greater than the third quartile, Q3?
Approximately what percentage of a data set is greater than the third quartile, Q3?
(A) about 25%
(B) about 50%
(C) about 75%
(D) about 100%
Answer: (C) about 25%
You want to measure the "physical fitness" of college students. Identify the example of a valid way to measure fitness.
You want to measure the "physical fitness" of college students. Identify the example of a valid way to measure fitness.
(A) Students' weight
(B) Students' height
(C) Students' grade point average
(D) Distance a student can run in some fixed length of time
Answer: (D) Distance a student can run in some fixed length of time
In a distribution that is skewed to the right, the mean tends to be
In a distribution that is skewed to the right, the mean tends to be
(A) greater than the median
(B) roughly equal to the median
(C) impossible to define
(D) less than the median
Answer: (A) greater than the median
A friend tells you, "In the 7:30 a.m. lecture for Statistics, 9 students failed. However, 20 students failed in the 1:30 p.m. class. The 1:30 p.m. professor is a tougher grader than the 7:30 a.m. teacher." Which of the following information will you require to conclude if 1:30 p.m. professor is a tougher grader than 7:30 a.m. professor?
A friend tells you, "In the 7:30 a.m. lecture for Statistics, 9 students failed. However, 20 students failed in the 1:30 p.m. class. The 1:30 p.m. professor is a tougher grader than the 7:30 a.m. teacher." Which of the following information will you require to conclude if 1:30 p.m. professor is a tougher grader than 7:30 a.m. professor?
(A) Class sizes
(B) Qualification of both professors
(C) Age of both professors
(D) Gender of both professors
Answer: (A) Class sizes
What is a good way to compare two numerical variables' distributions graphically?
What is a good way to compare two numerical variables' distributions graphically?
(A) Side-by-side interquartile ranges (B) Side-by-side boxplots
(C) Side-by-side bar graphs
(D) Side-by-side bar pictograms
Answer: (B) Side-by-side boxplots
A scale that always produces a weight reading that is 4 pounds too high has
A scale that always produces a weight reading that is 4 pounds too high has
(A) bias and high reliability
(B) bias and poor reliability
(C) no bias and high reliability
(D) no bias and poor reliability
Answer: (A) bias and high reliability
Colleges announce an average SAT score for their entering freshmen. Usually a college would like this average to be as high as possible. A New York Times article noted, "Private colleges that buy lots of top students with merit scholarships prefer the mean, while open-enrollment public institutions like medians." Which of the following statements correctly explains these preferences?
Colleges announce an average SAT score for their entering freshmen. Usually a college would like this average to be as high as possible. A New York Times article noted, "Private colleges that buy lots of top students with merit scholarships prefer the mean, while open-enrollment public institutions like medians."
Which of the following statements correctly explains these preferences?
(A) The relatively small number of top students does not affect the mean. The typical score, or the median, decreases by the presence of these students.
(B) The relatively small number of top students puts the mean above the median. The typical score, or the median, is not affected by the presence or absence of these students.
(C) Neither the median nor the mean is affected by the relatively small number of top students, and so both measures of center are equal in this case.
(D) The relatively small number of top students puts the mean below the median. The typical score, or the median, increases by the presence of these students.
Answer: (B) The relatively small number of top students puts the mean above the median. The typical score, or the median, is not affected by the presence or absence of these students.
If an ordinary coin has been tossed 10 times, and each of the last 5 tosses have resulted in "tails" then what is the probability of "tails" on the next toss?
If an ordinary coin has been tossed 10 times, and each of the last 5 tosses have resulted in "tails" then what is the probability of "tails" on the next toss?
(A) Around 0.50, because heads and tails should be equally likely.
(B) Less than 0.50, because the coin is due to come up "heads" by the law of averages.
(C) More than 0.50, because "tails" is currently on a hot streak.
(D) Either 0 or 1, because either a "heads" or a "tails" is certain to occur on the next toss.
Answer: (A) Around 0.50, because heads and tails should be equally likely.
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