1. Is gardening good for your health? A researcher observes that individuals who spend at least 10 hours per week gardening (or working in their gardens) have higher levels of Vitamin D than individuals who do little to no gardening each week. What would the response variable be in this study?

choose correct answer

A. Whether the garden includes vegetables or flowers

B. Amount of time spent gardening

C. Age of the individual

D. Size of the garden

E. Vitamin D level

2. Is whole-fat milk as good for children as low-fat milk? A sample of 49 children between the ages of 4 and 6 years old were followed for three months. Each child was randomly assigned to consume, on a daily basis, either low-fat milk or whole-fat milk. The milk was delivered to the children's homes each night to ensure that their parents did not have to pay for the milk, and the milk was presented in plain packaging so that neither the parents nor the children knew if they were consuming low-fat or whole-fat milk. At the start of the study, measurements were taken of each child's body mass index (or BMI), blood pressure, and general cardiovascular health. The same measurements were taken at the end of the study, after three months of daily consumption of either low-fat or whole-fat milk. If neither the researchers nor the participants knew who was consuming which type of milk, we'd say we have a ________

Chooose correct answer

A. placebo effect.

B. statistically significant result.

C. double-blind study.

D. Hawthorne effect.

E. nonresponse error.

3. Someone who does not follow an experimental treatment is called a _______

Choose correct answer

A. nonadherer.

B. lurking variable.

C. dropout.

D. margin of error.

E. confounder.

4. A large polling firm wants to understand if certain incentives might motivate individuals to complete surveys. They create a survey and select a large random sample of individuals to receive the survey. The individuals are randomly assigned to receive either (a) a survey with no incentive for completion, (b) a survey that includes a $5 gift card as a "thank you" for completing the survey, or (c) a survey that promises to give the individual a $5 gift card as a "thank you" after the completed survey is returned. The polling firm finds that those individuals who receive either a $5 gift card or the promise of a $5 gift card are more likely to complete the survey than those who receive no incentive for completion. In this study, how many treatments do we have?

Choose the correct answer

A. one

B. two

C. three

D. four

E. It's impossible to answer this question without knowing the total number of individuals who were selected to participate in the study.

5. A total of 600 volunteers who have precancerous skin lesions agree to participate in a medical experiment. Half (or n = 300) of these participants are given a skin cream that includes a large level of sun protection. The other half (or n = 300) are given an inert cream that contains no active ingredients at all. After 7 months, it is observed that those participants who used the cream with the large level of sun protection had fewer new precancerous lesions than those who used the cream with no active ingredients. We would call the cream that contained no active ingredients a __________

Choose the correct answer

A. confounder.

B. placebo.

C. response variable.

D. double-blind factor.

E. nonadherer.

6. If we have used random sampling in an experiment, this means we have used impersonal chance to

Choose the correct answer

A. decide who will be conducting the experiment.

B. select the treatments that will be included in the experiment.

C. determine which subjects get which treatments.

D. determine how the results of an experiment will be analyzed.

E. select subjects from the population to be in the experiment.

7. A comprehensive study of yogurt is conducted by a grocery store chain. In the study, researchers examine the sugar, fat, protein, and calcium contents of 921 different yogurt products. The individuals in this study would be

Choose the correct answer

A. the yogurt products.

B. the researchers.

C. the people who purchase the yogurt products.

D. the nutrient contents of the yogurt products.

E. the supermarkets where the yogurt products are sold.

9. What is the main difference between an observational study and an experiment?

Choose correct answer

A. There is no difference; the term "observational study" is just another name for "experiment."

B. An observational study only includes a small number of subjects, but an experiment always involves a large number of

subjects.

C. An observational study imposes treatments on the subjects, but an experiment study does not.

D. An observational study does not impose treatments on the subjects, but an experiment does.

E. Observational studies can have variables, but experiments cannot have variables.

10. College students are randomly assigned to either chew gum while studying a mathematics lesson or to not chew gum while studying the lesson. At the end of the lesson, the students complete a test about the contents of the lesson. Those students who chewed gum during the lesson correctly answered more test questions than those students who did not chew gum during the lesson. If the results of the study are said to be "statistically significant," what does this mean?

Choose correct answer

A. Teachers will now be required to distribute chewing gum to their students in order to help the students learn.

B. The difference in test scores between the groups was of a size that would almost never happen just by chance.

C. There was a placebo effect in this study.

D. The study was double-blind.

E. There must have been multiple lurking variables involved in the study.