Which of the following is not an assumption of the Chi Square Test?

a) each person may contribute only one response to the contingency table 

b) the variables are measured on either an interval or ratio scale 

c) there are at least 10 responses obtained in each cell of a 2x2 table 

d) there are at least 5 responses obtained in each cell of a 2x3 or larger table

Answer: B

In a two factor between subjects analysis of variance, where the interaction is statistically significant, MSaxb represents the variance due to?

a) the interaction of Factor A with Factor B, and error variance 

b) the effects of Factor A, Factor B and error variance 

c) the interaction of Factor A with factor B 

d) the effects of treatment Factor A and error variance 

e) error variance

Answer: A

In a two-factor between subjects analysis of variance, where Factor A is statistically significant, MSa is the variance due to 

a) the interaction of the two treatment factors and error variance 

b) the effect of Factor A

c) the effect of Factor A with Factor B removed 

d) the effects of Factor A and error variance 

e) error variance

Answer: D

What happens if three predictors are highly correlated in collinearity?

Answer: they are predicting the same variance in Y

What is the best way to make direct comparisons

Answer: compare predictors's betas or standardized slopes

What happens if the three predictors are perfectly correlated

Answer: one goes into the equation because there is nothing the other two could add

Treatment of breast cancer is a controversial issue with treatment varying from radical mastectomy to radiation and chemotherapy combined with simple lumpectomy. One long-term study involved noting survival times of all breast cancer patients from over 100 hospitals and comparing the percentage of women still alive 5 years after radical mastectomies with the percentage of women still alive 5 years after radiation and chemotherapy combined with simple lumpectomy. The results seems to show a better outcome for women who received lumpectomy treatment. Which of the following statements are appropriate?

I. This appears to be a well-conducted controlled experiment.

II. This observational study should be faulted for a lack of blinding.

III. A lurking variable involving who received what treatment makes any conclusion suspect.

A) I only

B) II only 

C) III only

D) I and II

E) II and III

Answer: III only

A drug company wishes to test a new drug. A researcher assembles a group of volunteers and randomly assigns them to one of two groups -- one to take the drug and one to take a placebo. In addition, the company wants the experiment to be double-blinded. What is the meaning of double-blind in this situation?

A) Neither the volunteers nor the drug company executives know which volunteers are take the drug and which are taking the placebo.

B) Neither the volunteers nor the evaluator know which volunteers are taking the drug and which are taking the placebo.

C) The volunteers in both groups do not know whether they are taking the drug or the placebo.

D) The volunteers in both groups are blindfolded when they take the drug or placebo.

E) As long as the subjects are randomly assigned to the two groups, there is no need to make the experiment double-blinded.

Answer: neither the volunteers nor the evaluator know which volunteers are taking the drug and which are taking the placebo

A researcher is testing the effect of a new fertilizer on crop growth. He marks 30 plots in a field, splits the plots in half, and randomly assigns the new fertilizer to one half of the plot and the old fertilizer to the other half. After 4 weeks, he measures the crop yield and compares the effects of the two fertilizers. This design is an example of

A) This is not an experiment

B) Double-blind experiment

C) Matched pairs experiment

D) Cluster experiment

E) Completely randomized comparative experiment

Answer: Matched pairs experiment

In a recent poll of 1,500 randomly selected eligible voters, only 525 (35%) said they did not vote in the last election. However, a vote count showed that 80% of eligible voters actually did not vote in the last election. Which of the following types of bias is most likely to have occurred in the poll?

A) Selection bias 

B) Sampling bias 

C) Nonresponse bias

D) Uncoverage bias

E) Response bias

Answer: Response bias

Which of these best explains why large samples tend to provide more reliable inferences about a population than small samples?

A) Large samples show less sampling variability.

B) The response variable will be measured more effectively.

C) It will be less of a problem if the randomization is imperfect.

D) There is a smaller probability of bias.

E) Large samples are more diverse.

Answer: large samples show less sampling variability

A television news editor would like to know how local registered voters respond to the question: "Are you in favor of the school bond measure that will be voted on in an upcoming special election?" A television survey is conducted during a break in the evening news by listing two telephone numbers side by side on the screen, one for viewer to call if they approve of the bond measure, and the other to call if they disapprove. This survey method could produce biased results for a number of reasons. Which of the following is the most obvious reason?

A) It uses a stratified sample rather than a simple random sample.

B) People who feel strongly about the issue are more likely to respond.

C) Some registered voters who call might not vote in the election.

D) Viewers should be told about the issues before the survey is conducted.

E) The wording of the question is biased.

Answer: people who feel strongly about the issue are more likely to respond

A 2008 ballot initiative in California sought a constitutional ban on same sex marriage. Suppose a survey prior to the election asked the question, "Do you favor a law that would eliminate the right of same sex couples to marry?" This question could produce biased results. Which of the following is the most likely reason?

A) Same sex couples are likely to be underrepresented in the sample.

B) The wording of the question could influence the response.

C) Only those who feel strongly about the issue are likely to respond.

D) Not all registered voters who respond to the survey are likely to vote.

E) Married couples are likely to vote the same way.

Answer: the wording of the question could influence the response

Which of the following is the best description of a systematic random sample?

A) After a population is separated into distinct groups, one or more of these groups are randomly selected in their entirety to be the sample.

B) A sample chosen in such a way that every possible sample of a given size has an equal chance to be the sample.

C) A value is randomly selected from an ordered list and then every nth value in the list after that first value is selected from the sample.

D) A sample in which respondents volunteer their response.

E) Select a sample in such a way that the proportion of some variables thought to impact the response is approximately the same in the sample as in the population.

Answer: a value is randomly selected from an ordered list and every nth value in the list after that first value is selected from the sample

A nutritional consulting company is trying to find what percentage of the population of a town is overweight. The marketing department contact by telephone 600 people from a list of the entire town's population. About 100 people give answers to the survey. Which of the following is the most significant source of bias in this survey?

A) Undercoverage 

B) Response bias 

C) Size of sample

D) Nonresponse

E) Voluntary response bias

Answer: Nonresponse

An experiment to measure the effect of giving hormones to girls affected by Turner's Syndrome was carried out recently in Vancouver. All 34 girls in the study were given the growth hormone and their heights were measured at the time the hormone was given and again one year later. No measurements were made on their final adult heights. Which of the following is not a problem with this experiment:

A) There was no control group.

B) Nonresponse bias

C) There was insufficient attention to the placebo effect.

D) Because final heights were not measured, it is impossible to tell if the hormone affected final height or only accelerated growth and made no difference to final height.

E) There was no blinding.

Answer: nonresponse bias

A researcher observes that, on average, the number of traffic violations in cities with Major League Baseball teams is larger than in cities without Major League baseball teams. The most plausible explanation for this observed association is that the

A) presence of a Major League baseball team causes the number of traffic incidents to rise (perhaps due to the large number of people leaving the ballpark.)

B) association is due to the presence of a lurking variable. (Major League teams tend to be in large cities with more people, hence a greater number of traffic incidents)

C) observed association is purely coincidental. It is implausible to believe the observed association could be anything other than accidental.

D) association makes no sense, since many people take public transit or walk to baseball games.

E) high number of traffic incidents is responsible for the presence of Major League baseball teams (more traffic incidents means more people have cars, making it easier for them to get to the ballpark.)

Answer: association is due to the presence of a lurking variable. (Major League teams tend to be in large cities with more people, hence a greater number of traffic incidents)

A cause-and-effect relationship between two variables can best be determined from which of the following?

A) A controlled experiment where the observational units are assigned randomly.

B) When the two variables have a correlation coefficient near 1.

C) A survey conducted using a simple random sample of individuals.

D) An observational study where the observational units are chosen randomly.

E) A survey conducted using a stratified random sample of individuals

Answer: a controlled experiment where the observational units are assigned randomly

Since many individuals walk around their homes in their socks, a manufacturer has created a material for socks that is believed to be more resistant to wear than cotton. The manufacturer wishes to test this belief over a period of a month. Given a group of volunteers, which of the following designs will best test this new material's resistance to wear?

A) Have the volunteers wear the socks made from the new material for a month, and check the wear on the socks at the end of the month.

B) Allow half of the volunteers to wear cotton socks, while the other half wear socks made of the new material. Compare the wear on the socks at the end of the month.

C) For each volunteer, randomly choose which foot wears a cotton sock, while the other foot wears a sock made of the new material. Compare the wear on the socks at the end of the month.

D) Randomly assign half of the volunteers to wear cotton socks, while the other half wear socks made of the new material. Compare the wear on the socks at the end of the month.

E) Randomly assign half of the volunteers to wear cotton socks, while the other half wear socks made of the new material. At the end of two weeks, the volunteers should change sock types. Compare the wear on the socks at the end of the month.

Answer: for each volunteer, randomly choose which foot wears a cotton sock, while the other foot wears a sock made of the new material. compare the wear on the socks at the end of the month

For a certain experiment you have 8 subjects, of which 4 are female and 4 are male. The names are Males: Atwater, Bacon, Chu, Diaz Females: Johnson, King, Liu, Moore. There are two treatments, A and B. If a randomized block design is used, with the subjects blocked by their gender, which of the following is NOT a possible group of subjects who receive treatment A?

A) Atwater, Bacon, Johnson, King 

B) Atwater, Diaz, Liu, King

C) Atwater, Chu, King, Liu

D) Bacon, Chu, Liu

E) Atwater, Bacon, Chu, Johnson

Answer: Atwater, Bacon, Chu, Johnson