Archive for December 2018

A researcher conducts a study to investigate the influence of the amount of noise in the environment on the number of errors a person makes. The following means were obtained. What conclusion should be drawn from this experiment?

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A researcher conducts a study to investigate the influence of the amount of noise in the environment on the number of errors a person makes. The following means were obtained. What conclusion should be drawn from this experiment?


Low | Med | High
x̄=7 | x̄=11 | x̄=14

A. Apparently, there is no relationship between noise level and number of errors.
B. Apparently, there is a relationship: as number of errors increases, the noise level also increases from around 7 to around 11 to around 14.
C. Apparently, there is a relationship: As the number of errors increases. the noise level also increases from low to medium to high.
D. Apparently there is a relationship: As the noise level increases, the number of errors also increases from around 7 to around 11 to around 14.


Answer: Apparently there is a relationship: As the noise level increases, the number of errors also increases from around 7 to around 11 to around 14.

An experimenter investigated the ability to concentrate as a function of eye color. Eye color was classified as having either, brown eye, or other eye color. which type of graph should the experimenter use to display the results?

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An experimenter investigated the ability to concentrate as a function of eye color. Eye color was classified as having either, brown eye, or other eye color. which type of graph should the experimenter use to display the results?



A. X and Y
B. Histogram
C. Bar
D. Line


Answer: Bar

On any graph a horizontal line of data points indicates that

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On any graph a horizontal line of data points indicates that



A. the Y scores are changing as the X scores change, and there is a relationship present.
B. The Y score are not changing as the X scores change, and there is no relationship present.
C. the independent and dependent variables have been placed on the wrong axes and should be reversed.
D. every score is occurring with a different frequency


Answer: The Y score are not changing as the X scores change, and there is no relationship present.

When we graph results from an Experiment, a line graph is appropriate when

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When we graph results from an Experiment, a line graph is appropriate when



A. The independent variable is interval or ratio
B. The independent variable is nominal or ordinal
C. The dependent variable is nominal or ordinal.
D. The dependent variable is interval or ratio


Answer: The independent variable is interval or ratio

When we graph the results of an experiment, the Y axis indicates the

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When we graph the results of an experiment, the Y axis indicates the



A. measure of central tendency we have used for the dependent variable.
B. Raw score values for each subject on the dependent variable.
C. Raw scores for each of the independent variable.
D. Levels of the independent variable.


Answer: measure of central tendency we have used for the dependent variable.

In a graph of the relationship between the level of nose in a environment and the number of errors a person makes, the ____ is on the X axis and the ____ is on the Y axis.

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In a graph of the relationship between the level of nose in a environment and the number of errors a person makes, the ____ is on the X axis and the ____ is on the Y axis.



A. Number of errors; frequency of errors
B. level of noise; number of errors
C. level of noise; frequency of noise
D. number of errors; level of noise


Answer: level of noise; number of errors

A researcher has conducted an experiment in which the independent variable is room temperature. Two conditions (a hot room and a cold room) were used. The dependent variable was the length of time required to complete a jigsaw puzzle. What is the best way to state the there is a relationship?

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A researcher has conducted an experiment in which the independent variable is room temperature. Two conditions (a hot room and a cold room) were used. The dependent variable was the length of time required to complete a jigsaw puzzle. What is the best way to state the there is a relationship?



A. The mean times to complete the puzzle are not different fro the two room conditions.
B. The mean room temperatures are not different for the length of time required to complete the jigsaw puzzle.
C. The mean times complete the puzzle are different for the two room conditions.
D.The mean room temperatures are different for the length of time required to complete the jigsaw puzzle.


Answer: The mean times complete the puzzle are different for the two room conditions.

The population mean is estimated by

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The population mean is estimated by



A. calculation the mean of as many scores as we can get from the population.
B. calculation the mean of a random sample drawn from the population.
C. calculating the mean of a random sample drawn from the population.
D. calculating all measures of central tendency for a random sample from the population.


Answer: calculation the mean of a random sample drawn from the population.

μ is the symbol for the

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μ is the symbol for the



A. population median.
B. population mode.
C. population mean.
D. sample mean.


Answer: population mean.

Five students took a personality test. Their deviation scores were -4 +3 +1 -2 +2. Assuming that these scores form a normal distribution, which of the following orders represents their ranking in terms if frequency, from highest to lowest?

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Five students took a personality test. Their deviation scores were -4 +3 +1 -2 +2. Assuming that these scores form a normal distribution, which of the following orders represents their ranking in terms if frequency, from highest to lowest?



A. +1, +2 and -2, +3, -4
B. -4, +3, +2 and -2, +1
C. -4, -2, +1, +2, +3
D. +3, +2, +1, -2, -4


Answer: +1, +2 and -2, +3, -4

A deviation score is more informative than a raw score because it

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A deviation score is more informative than a raw score because it



A. describes the shape of the distribution.
B. has a greater numeric value.
C.. is a transformation of the raw score.
D. gives the score's location relative to the mean.


Answer: gives the score's location relative to the mean.

When the mean is used to predict scores, a deviation (x - x̄) indicates

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When the mean is used to predict scores, a deviation (x - x̄) indicates



A. the sample is representative of the population.
B. the difference between the x̄ we predict and the score an individual actually gets.
C. the sum of all the deviations.
D. the individual's observed score.


Answer: the difference between the x̄ we predict and the score an individual actually gets.

When using the mean to predict scores, error is represented by.

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When using the mean to predict scores, error is represented by.



A. the deviation of the median from the mean.
B. a statistic obtained from a nonrandom sample.
C. the deviation of a score from the mean.
D. the differences between raw scores in a sample.


Answer: the deviation of a score from the mean.

The equipment failed to record the reaction time for one trial in an experiment. The reaction times (in milliseconds)) for the other trials were 505, 630, 490, 650, and 560. What is the best guess for the missing value?

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The equipment failed to record the reaction time for one trial in an experiment. The reaction times (in milliseconds)) for the other trials were 505, 630, 490, 650, and 560. What is the best guess for the missing value?



A. 490.00
B. 560.
C. 567.00
D. 568.75


Answer: 567.00

A score's deviation conveys two pieces of information about the score's location: the number indicates _____, and the sign indicates _____.

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A score's deviation conveys two pieces of information about the score's location: the number indicates _____, and the sign indicates _____.




A. The score's distance from the mean; whether the score is greater or less than the mean.
B. whether the score is greater or less than the mean; the score's distance from the mean.
C. The size of the score; whether the score is a good score.
D. whether the score is a good score; whether the score is positive or negative.


Answer: The score's distance from the mean; whether the score is greater or less than the mean.

The mean is used most often in behavioral research because researchers tend to

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The mean is used most often in behavioral research because researchers tend to




A. Measure variables that have interval or ratio scores, and the scores form approximately normal distributions.
B. conduct research in which the mathematical center of a distribution is required.
C. conduct research in which only the most frequently occurring score is needed.
D. Measure variables that have interval or ratio scores, and the scores usually do not form a normal distribution.


Answer: Measure variables that have interval or ratio scores, and the scores form approximately normal distributions.

When we refer to a score's deviation, we are referring to

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When we refer to a score's deviation, we are referring to



A. how far it is from other scores.
B. how far it is from the mean.
C. how close it is to the other scores.
D. how much error occurred in measuring it.


Answer: how far it is from the mean.

The distribution of weights of men in the American population is not symmetrical. Most weights are bunched together at the lower end of the distribution. As weights increase, there are fewer and fewer men with these weights. how would you describe the relationship between the mean, the median, and the mode in this distribution?

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The distribution of weights of men in the American population is not symmetrical. Most weights are bunched together at the lower end of the distribution. As weights increase, there are fewer and fewer men with these weights. how would you describe the relationship between the mean, the median, and the mode in this distribution? 



A. mode < median < mean
B. mean < median < mode
C. mean = median = mode
D. median < mode < mean


Answer: mode < median < mean

The mean is inappropriate measure of central tendency when the distribution is severely skewed because

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The mean is inappropriate measure of central tendency when the distribution is severely skewed because



A. it is not the mathematical center of a skewed distribution.
B. only 50% of the scores in a skewed distribution are near it.
C. it does not accurately describe a skewed distribution.
D. only the mode describes a skewed distribution.


Answer: it does not accurately describe a skewed distribution.

In a skewed distribution the mathematical center is

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In a skewed distribution the mathematical center is



A. the median, which is the point around which most of the scores tend to be located.
B. the mode, which is the point around which most of the scores tend to be located.
C. the mean, which is not the point around which most of the scores tend to be located.
D. impossible to determine.


Answer: the mean, which is not the point around which most of the scores tend to be located.

An experimenter investigated the ability to concentrate as a function of crowding. Concentration was measured as the amount of time it took the participant to complete a word puzzle. How should the experimenter summarize the scores on the dependent variable?

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An experimenter investigated the ability to concentrate as a function of crowding. Concentration was measured as the amount of time it took the participant to complete a word puzzle. How should the experimenter summarize the scores on the dependent variable?



A. Find the mode for crowding because crowding scores are nominal.
B. Find the mean amount of crowding if the crowding scores are normally distributed.
C. Find the mean amount of time it took to solve the puzzle, if time scores are normally distributed.
D. Find the median amount of time it took to solve the puzzle because time scores are ordinal.


Answer: Find the mean amount of time it took to solve the puzzle, if time scores are normally distributed.

The mean is the preferred measure of central tendency when

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The mean is the preferred measure of central tendency when



A. the scale of measurement is interval.
B. the scale of measurement is ordinal, interval, or ratio and the distribution is skewed.
C. the scale of measurement is ratio.
D. the distribution is symmetrical and the scale of measurement is interval or ratio.


Answer: the distribution is symmetrical and the scale of measurement is interval or ratio.

To obtain the mean, we would

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To obtain the mean, we would



A. count all the scores and divide by the total number of scores.
B. add all the scores and divide by the sum of all the scores.
C. divide the total number of scores by the sum of all the scores.
D. add all the scores and divide by the total number of scores.


Answer: add all the scores and divide by the total number of scores.

The mean is defined as

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The mean is defined as



A. the most frequently occurring score.
B. the mathematical center of the distribution.
C. the smallest deviation from the center score.
D. the point at or below which 50% of the scores fall.


Answer: the mathematical center of the distribution.

Why is the median unaffected by extreme scores occurring in only one tail of the distribution.

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Why is the median unaffected by extreme scores occurring in only one tail of the distribution.



A. because the median does not take into account the actual values of all the scores.
B. because the median takes into account the actual values of all the scores.
C. because the median is only one point in the while distribution.
D. because the median is based on how frequently the median score occurs.


Answer: because the median does not take into account the actual values of all the scores.

The median is the preferred measure of central tendency when

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The median is the preferred measure of central tendency when



A. the scale of measurement is nominal.
B. the scale of measurement is ordinal.
C. the scale of measurement is ratio.
D. the distribution is symmetrical and the scale of measurement is interval or ratio.


Answer: the scale of measurement is ordinal.

The median is defined as

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The median is defined as



A. the mostly frequently occurring score.
B. the mathematical center of the distribution.
C. the smallest deviation from the mean.
D. the point at or below which 50% of the scores fall.


Answer: the point at or below which 50% of the scores fall.

The mode is defined as

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The mode is defined as



A. the most frequently occurring score.
B. the mathematical center of the distribution.
C. the smallest deviation from the mean.
D. the point at or below which 50% of the scores fall.


Answer: the most frequently occurring score.

In order to decide which measure of central tendency is appropriate you must first determine

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In order to decide which measure of central tendency is appropriate you must first determine



A. the appropriate graph to use and the independent variable.
B. the independent and the dependent variables.
C. how the data will be collected.
D. the scale of measurement being used and the shape of the distribution.


Answer: the scale of measurement being used and the shape of the distribution.

With respect to other scores in a distribution, measures of central tendency

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With respect to other scores in a distribution, measures of central tendency



A. are all around the other scores.
B. are the points around which most of the scores are located.
C. usually fall in the tails or extremes of the distribution.
D. are never actually equal to one of those scores in the distribution.


Answer: are the points around which most of the scores are located.

An individual being tested for a gifted program scores a 132 on the Cognitive Ability Test (CogAT), which has a mean of 100 and a standard deviation of 16. There is a .40 correlation between the CogAT score and success as measured by GPA in the gifted program, which has a weighted mean of 4.3 with a SD of .2. Use the Standard Error of the Estimate (SEest) to predict where this students GPA will fall 68 percent of the time.

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An individual being tested for a gifted program scores a 132 on the Cognitive Ability Test (CogAT), which has a mean of 100 and a standard deviation of 16. There is a .40 correlation between the CogAT score and success as measured by GPA in the gifted program, which has a weighted mean of 4.3 with a SD of .2. Use the Standard Error of the Estimate (SEest) to predict where this students GPA will fall 68 percent of the time.



a. None of these
b. 4.7 ± .18
c. 4.5 ± .4
d. 4.7 ± .15
e. 4.3 ± .2


Answer: b. 4.7 ± .18

A test to measure psychotic tendencies was given to a group of 1,000 potential air force cadets who wished to work in nuclear silos. Any cadet who scored at or over a 64 would be eliminated. The mean of the test was 52 and the standard deviation was 12. Of the following scores, which is the highest z-score someone could receive and still be accepted to work in the silos?

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A test to measure psychotic tendencies was given to a group of 1,000 potential air force cadets who wished to work in nuclear silos. Any cadet who scored at or over a 64 would be eliminated. The mean of the test was 52 and the standard deviation was 12. Of the following scores, which is the highest z-score someone could receive and still be accepted to work in the silos?



a. 1.5
b. 2
c. 0
d. 2.5
e. 3


Answer: c. 0

Which of the following is NOT always true?

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Which of the following is NOT always true?



a. All of these are true.
b. If you know the z score, you can determine the standard deviation of the test.
c. If you know the z score, you can determine most common standard scores (e.g., T score, DIQ, SAT, NCE, etc.).
d. If you know the z score, you can determine a percentile by looking at a conversion chart.


Answer: b. If you know the z score, you can determine the standard deviation of the test.d. If you know the z score, you can determine a percentile by looking at a conversion chart.

This act or law assures the privacy of client records, including testing records, and the sharing of such information.

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This act or law assures the privacy of client records, including testing records, and the sharing of such information.



a. Carl Perkins Act (PL 98-524)
b. FERPA
c. Freedom of Information Act
d. Health Insurance Portability and Accountability Act (HIPAA)
e. Civil Rights Acts (1964 and amendments)


Answer: d. Health Insurance Portability and Accountability Act (HIPAA)

This law assures the right of individuals to access their federal records, including test records. Most states have similar laws that assure the right to access of state records.

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This law assures the right of individuals to access their federal records, including test records. Most states have similar laws that assure the right to access of state records.



a. Carl Perkins Act (PL 98-524)
b. Civil Rights Acts (1964 and amendments)
c. Americans with Disabilities Act
d. Freedom of Information Act
e. FERPA


Answer: d. Freedom of Information Act

A counselor can break confidentiality in all EXCEPT which of the following?

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A counselor can break confidentiality in all EXCEPT which of the following?



a. For purposes of supervision
b. If the client gives the counselor permission to break confidentiality
c. If a client is in danger of harming self or another person
d. A counselor can break confidentiality for all of these reasons.
e. If a parent asks for information about his or her young child


Answer: d. A counselor can break confidentiality for all of these reasons.

Relative to assessment, which of the following are NOT addressed in ethical codes?

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Relative to assessment, which of the following are NOT addressed in ethical codes?



a. Proper test administration
b. The use of diagnosis in the assessment process
c. The importance of test security
d. Specific ethical decision making models (e.g., Corey, Remley & Herlihy)
e. Proper test scoring and interpretation


Answer: d. Specific ethical decision making models (e.g., Corey, Remley & Herlihy)

Why is diagnosis important in the assessment process?

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Why is diagnosis important in the assessment process?



a. All of these are reasons why diagnosis is important in the assessment process.
b. It provides different ways of treating the client as a function of the clinician's theoretical orientation.
c. It provides an understanding of the etiology of the mental disorders.
d. It offers one additional means of understanding the whole person.


Answer: d. It offers one additional means of understanding the whole person.

Which of the following is true about subtypes in the DSM-5?

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Which of the following is true about subtypes in the DSM-5?



a. They help capture the severity of an illness.
b. They are mutually exclusive - you can only pick one.
c. They are used to communicate the dimensional diagnosis.
d. They are identified by the phrase "specify if."


Answer: b. They are mutually exclusive - you can only pick one.

On a negatively skewed curve, which of the following statements is true?

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On a negatively skewed curve, which of the following statements is true?



a. The mean, median, and mode is the same.
b. The mode is lower than the mean which is lower than the median.
c. The median is lower than the mode which is lower than the mean.
d. The mean is lower than the mode which is lower than the median.
e. The mean is lower than the median which is lower than the mode.


Answer: e. The mean is lower than the median which is lower than the mode.

Jerome has scored a 10 on a test. How has he done?

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Jerome has scored a 10 on a test. How has he done?



a. We should ask Jerome how he thinks he has done. His thoughts about his score are part of what determines how he has done.
b. On some tests, this might be indicative of a moderate score.
c. On some tests, this might be indicative of a very poor score.
d. All of these are true.
e. On some tests, this might be indicative of a very good score.


Answer: d. All of these are true.

In neuropsychological assessment, an individual's scores are best compared against which of the following?

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In neuropsychological assessment, an individual's scores are best compared against which of the following?



a. A large normative sample based on U.S. census data stratified for gender, age, race, and geographical region
b. The estimated level of functioning of your individual before onset of the illness
c. A norm group of both healthy "normal" individuals and those suffering from a wide variety of mental illness
d. A norm group consisting of individuals who have the same psychopathology as your client
e. None of these


Answer: b. The estimated level of functioning of your individual before onset of the illness

Which of the following is true about the Wechsler tests?

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Which of the following is true about the Wechsler tests?



a. The WISC-IV is a downward extension of the WAIS-IV, and the WPPSI-III is a downward extension of the WISC-IV.
b. The three tests are used for individuals aged 2 through 90, based on expected intellectual levels.
c. The tests have been created independently, and have little in common.
d. The tests show little or no correlation with the Stanford-Binet.


Answer: a. The WISC-IV is a downward extension of the WAIS-IV, and the WPPSI-III is a downward extension of the WISC-IV.

Which is NOT one of Guilford's cognitive abilities?

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Which is NOT one of Guilford's cognitive abilities?



a. Operations, or the processes we use in understanding
b. Contents, or what we use to perform our thinking process
c. Functions, or the way that cognitive structures work
d. Product, or the end result of our thinking processes


Answer: c. Functions, or the way that cognitive structures work

Spearman's two factor approach included:

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Spearman's two factor approach included:



a. higher order and lower order intelligence.
b. the process factors of assimilation and accommodation.
c. a general factor (g) and a specific factor (s).
d. fluid, culturally free intelligence, and crystallized, learned intelligence.


Answer: c. a general factor (g) and a specific factor (s).

Which of the following is NOT a use of intelligence testing?

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Which of the following is NOT a use of intelligence testing?



a. To assist in determining giftedness
b. Intelligence testing is used for all of these reasons.
c. To help understand changes in brain function as a result of accidents, dementia, the aging process, abuse, and disease processes
d. To assist in determining certain types of learning disabilities
e. To assist in determining mental retardation


Answer: b. Intelligence testing is used for all of these reasons.

PL 94-142 and the IDEIA asserted:

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PL 94-142 and the IDEIA asserted:



a. accommodations must be made for individuals who are taking tests for employment and testing must be shown to be relevant to the job in question.
b. the right of students to be tested, at a school system's expense, if they are suspected of having a disability that interferes with learning.
c. individuals with disabilities, or who are disadvantaged, have access to vocational assessment, counseling, and placement.
d. the right of all individuals to their school records, including test records.


Answer: b. the right of students to be tested, at a school system's expense, if they are suspected of having a disability that interferes with learning.

A test developer creates a new instrument to measure depression. He correlates this instrument with an existing test that measures anxiety. The test developer hopes to not find a high correlation, thus assuring the integrity of the construct he is measuring. This type of validity is called:

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A test developer creates a new instrument to measure depression. He correlates this instrument with an existing test that measures anxiety. The test developer hopes to not find a high correlation, thus assuring the integrity of the construct he is measuring. This type of validity is called:



a. factor analysis validity.
b. criterion-related validity.
c. convergent validity.
d. experimental design validity.
e. discriminant validity.


Answer: e. discriminant validity.

Which is NOT a diagnostic test?

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Which is NOT a diagnostic test?



a. The Peabody Individual Achievement Test
b. The Wide Range Achievement Test 4 (WRAT4)
c. All of these are diagnostic tests.
d. The Woodcock Johnson III
e. The Wechsler Individual Achievement Test-Second Edition (WIAT-II)


Answer: c. All of these are diagnostic tests.

Which of the following is NOT a use of tests of educational ability?

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Which of the following is NOT a use of tests of educational ability?



a. To assist in career and occupational assessment
b. To help determine if a child is ready to move to the next grade level
c. To assist in the determination of giftedness
d. To assess how well a class, grade, school, school system, or state is learning content knowledge
e. To assist in the determination of learning problems


Answer: a. To assist in career and occupational assessment

On a negatively skewed curve, which of the following statements is true?

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On a negatively skewed curve, which of the following statements is true?



a. The mean, median, and mode is the same.
b. The mode is lower than the mean which is lower than the median.
c. The median is lower than the mode which is lower than the mean.
d. The mean is lower than the mode which is lower than the median.
e. The mean is lower than the median which is lower than the mode.


Answer: e. The mean is lower than the median which is lower than the mode.

Jerome has scored a 10 on a test. How has he done?

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Jerome has scored a 10 on a test. How has he done?



a. We should ask Jerome how he thinks he has done. His thoughts about his score are part of what determines how he has done.
b. On some tests, this might be indicative of a moderate score.
c. On some tests, this might be indicative of a very poor score.
d. All of these are true.
e. On some tests, this might be indicative of a very good score.


Answer: d. All of these are true.

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He uses a random number generator to pick 4 of the 23 aisles, and then asks all of the customers in those aisles whether they are comfortable.

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What survey methodology is this?

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He uses a random number generator to pick 4 of the 23 aisles, and then asks all of the customers in those aisles whether they are comfortable.



A: Stratified Sampling
B: Clustered Sampling
C: Simple Random Sampling
D: Systematic Sampling


Answer: B

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He knows men and women may have different views, and also knows 60% of his customers are women. He asks a random 60 women and a random 40 men whether they are comfortable.

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What survey methodology is this?

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He knows men and women may have different views, and also knows 60% of his customers are women. He asks a random 60 women and a random 40 men whether they are comfortable. 



A: Stratified Sampling
B: Clustered Sampling
C: Simple Random Sampling
D: Systematic Sampling


Answer: A

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He uses a random number generator to select customers at random and asks them whether they are comfortable.

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What survey methodology is this?

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He uses a random number generator to select customers at random and asks them whether they are comfortable. 



A: Stratified Sampling
B: Clustered Sampling
C: Simple Random Sampling
D: Systematic Sampling


Answer: C

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He surveys every 10th customer that comes into the store and asks them whether they are comfortable, yes or no.

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What survey methodology is this?

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He surveys every 10th customer that comes into the store and asks them whether they are comfortable, yes or no. 



A: Stratified Sampling
B: Clustered Sampling
C: Simple Random Sampling
D: Systematic Sampling


Answer: D

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He surveys every 10th customer after they leave and are getting into their cars whether they are warm enough.

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What is wrong with this survey?

The manager of a QFC is concerned that customers may think the store's temperature may be too warm. He surveys every 10th customer after they leave and are getting into their cars whether they are warm enough. 



A: The wrong question
B: The wrong sampling frame
C: A biased sample


Answer: A

An amusement park opens a new roller coaster. It is so popular that people are waiting for up to 3 hours. The owners want to know how the visitors feel. They survey every 10th person in the line for the roller coaster, starting from a randomly selected individual.

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What is wrong with this survey?

An amusement park opens a new roller coaster. It is so popular that people are waiting for up to 3 hours. The owners want to know how the visitors feel. They survey every 10th person in the line for the roller coaster, starting from a randomly selected individual. 



A: The wrong question
B: The wrong sampling frame
C: A biased sample


Answer: B

Lycos wanted to know what people thought about medical marijuana. They posted a question on the Lycos Website on 18 June 2000: Should marijuana be legally available for medical purposes?

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What is wrong with this survey?

Lycos wanted to know what people thought about medical marijuana. They posted a question on the Lycos Website on 18 June 2000: Should marijuana be legally available for medical purposes? 



A: The wrong question
B: The wrong sampling frame
C: A biased sample


Answer: C

How do we use the five-number summary to make a modified boxplot?

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How do we use the five-number summary to make a modified boxplot?



Answer: A modified boxplot is a graph of the 5-number summary, with outliers plotted individually.


- a central box spans the quartiles
- a line in the box marks the median
- observations more than 1.5*IQR outside the central box are plotted individually
- lines extend from the box out to the smallest and largest observations that are not outliers

Explain how to calculate Q1 and Q3.

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Explain how to calculate Q1 and Q3.



Answer:

1) arrange the observations in increasing order and locate the median M in the list.
2) Q1 is the median of the observations whose position in the ordered list is to the left of the location of the overall median.
3) Q3 is the median of the observations whose position in the ordered list is to the right of the location of the overall median.

In statistics, what is meant by spread?

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In statistics, what is meant by spread?




Answer: Spread is a way to measure the variability of the observations around the center. One of the most common ways to measure spread is to calculate the range of the data. The range is obviously sensitive to extreme measures.

Explain why the median is resistant to extreme observations, but the mean is nonresistant.

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Explain why the median is resistant to extreme observations, but the mean is nonresistant.



Answer: The median is resistant because it is only based on the middle one or two observations of the ordered list. The mean is sensitive to the influence of a few extreme observations. Even if there are no outliers a skewed distribution will pull the mean toward the long tail.

Explain how to calculate the median, M.

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Explain how to calculate the median, M.



Median M is the midpoint of a distribution, the number such that half the observations are smaller and the other half are larger. To find the median:

1) arrange all the observations in order of size, from smallest to largest
2) if the number of observations is odd, the median M is the center observation of the order list.
3) if the number of observations is even, the median M is the mean of the 2 center observations in the ordered list.

Define outlier.

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Define outlier.





Answer: an individual observation that falls outside the overall pattern of the graph.

Define range.

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Define range.





Answer: the difference between the largest and smallest values of data distribution.

When is it useful to use a bar chart? Or a pie chart?

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When is it useful to use a bar chart? Or a pie chart?



Answer: Bar charts and pie charts are both used to display categorical data. A pie chart cannot be used unless we have information about all the categories to total 100%.

What is meant by exploratory data analysis?

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What is meant by exploratory data analysis?



Answer: Exploratory data analysis uses graphs and numerical summaries to describe the variables in a data set and the relations among them.

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