Question 1

Which of the following best describes a confounding variable in a statistical study?

Accepted Answer

A variable that is associated with both the explanatory and response variables, offering a plausible explanation for their association.

Question 2

A pharmaceutical company wants to test whether a new drug reduces blood pressure compared to a placebo. Participants are randomly assigned to either the drug or placebo group. What type of study is this?

Accepted Answer

Randomized comparative experiment

Question 3

Which statement correctly distinguishes between association and causation?

Accepted Answer

Association means that knowing the value of one variable gives extra information about the other, but does not imply that one causes the other.

Question 4

In a double-blind experiment, who is unaware of which treatment group participants are in?

Accepted Answer

Both the participants and the researchers administering the treatment

Question 5

A study finds that people who exercise regularly have lower rates of heart disease. However, diet is not measured. What type of variable could diet be in this study?

Accepted Answer

Lurking variable

Question 6

Which of the following is a reason why observational studies cannot easily establish cause-and-effect relationships?

Accepted Answer

Confounding variables are difficult to control in observational studies.

Question 7

A researcher wants to compare the effect of two diets on cholesterol levels. Each participant tries both diets in random order. What type of experiment is this?

Accepted Answer

Matched-pairs experiment

Question 8

Which of the following best describes the placebo effect?

Accepted Answer

Participants respond to the idea that they are being treated, even if the treatment is inactive.

Question 9

Why is replication important in experiments?

Accepted Answer

It increases confidence that the observed association is not due to random chance and can be accepted as scientific fact.

Question 10

Which of the following is NOT a possible explanation for an observed association between two variables?

Accepted Answer

The association is always due to the explanatory variable.

Question 11

A study randomly selects participants from a population and randomly assigns them to receive either a new medication or a placebo. Which two types of randomization are being used?

Accepted Answer

Random selection and random assignment

Question 12

In an experiment testing a new teaching method, the control group receives the standard teaching method. What is the purpose of the control group?

Accepted Answer

To provide a baseline for comparison with the new teaching method.

Question 13

Which of the following statements is true regarding blinding in experiments?

Accepted Answer

Blinding helps reduce response bias by preventing knowledge of treatment assignment.

Question 14

A study finds a strong association between ice cream sales and drowning incidents. Which of the following is most likely a confounding variable?

Accepted Answer

Temperature (season)

Question 15

Which of the following best describes an observational study?

Accepted Answer

Researchers observe values as they naturally exist without controlling any variables.

Question 16

In a study, participants are told they will receive either a new drug or a placebo, but neither they nor the administering nurse knows which they receive. What is this an example of?

Accepted Answer

Double-blind experiment

Question 17

Which of the following is a synonym for association, as used in scholarly journals?

Accepted Answer

Relationship

Question 18

A study claims that 'taking a practice test improves your score.' Which type of association is being claimed?

Accepted Answer

Causal association

Question 19

Which of the following is a key difference between confounding and lurking variables?

Accepted Answer

Lurking variables are not considered in the study, while confounding variables are included but their effects cannot be separated from other explanatory variables.

Question 20

Which of the following best describes the purpose of random assignment in experiments?

Accepted Answer

To attribute observed associations to cause-and-effect by reducing confounding.

Experiments and Observational Studies: Association, Causation, and Confounding

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