Question 1

Which of the following best describes an observational study?

Accepted Answer

Researchers observe or measure characteristics of subjects without attempting to influence or modify them.

Question 2

A study is conducted to determine whether a new herbal remedy reduces the severity of colds. Subjects are randomly assigned to receive either the remedy or a placebo. Which type of study is this?

Accepted Answer

Experiment

Question 3

In an experiment, what is the primary purpose of the control group?

Accepted Answer

To serve as a baseline for comparison by not receiving the treatment

Question 4

Which of the following is an example of a prospective study?

Accepted Answer

Researchers set up a study to follow a group of people over several years to see if they develop heart disease.

Question 5

A variable that may explain or cause an effect in a statistical study is called:

Accepted Answer

Explanatory variable

Question 6

In a study, college students are asked if they commute or live on campus. What is the response variable?

Accepted Answer

Whether the student commutes or lives on campus

Question 7

Which of the following best describes a retrospective study?

Accepted Answer

Data are collected from the past, such as official records or interviews.

Question 8

A study suffers from confounding when:

Accepted Answer

The effects of different variables are mixed, making it impossible to determine the individual effects.

Question 9

Which strategy is most effective in avoiding confounding in an experiment?

Accepted Answer

Using sufficiently large groups and random assignment

Question 10

In a double-blind experiment:

Accepted Answer

Neither the subjects nor the experimenters know who is in the treatment or control group.

Question 11

A placebo is used in experiments to:

Accepted Answer

Prevent subjects from knowing whether they are receiving the real treatment

Question 12

Which of the following best illustrates the placebo effect?

Accepted Answer

Subjects improve simply because they believe they are receiving a useful treatment.

Question 13

A meta-analysis is characterized by:

Accepted Answer

Reviewing many published studies as a combined group to find trends.

Question 14

In the experiment where college students listen to classical music before a task, what is the treatment?

Accepted Answer

Listening to classical music before the task

Question 15

Which of the following is a potential problem in an experiment where only six subjects are divided into treatment and control groups?

Accepted Answer

The sample size is too small, increasing the risk of confounding.

Question 16

In a single-blind experiment, who is unaware of group assignments?

Accepted Answer

Only the subjects

Question 17

Which of the following best describes the experimenter effect?

Accepted Answer

Researchers influence subjects through facial expressions, tone of voice, or attitude.

Question 18

A chiropractor performs adjustments on 25 patients with back pain. Afterward, 18 say they feel better. What is a major flaw in this study?

Accepted Answer

No control group is used for comparison.

Question 19

Which equation best represents the probability of randomly assigning a subject to either the treatment or control group in an experiment with $$n$$ subjects?

Accepted Answer

$$P = \frac{1}{2}$$

Question 20

Suppose researchers want to study whether seat belts save lives. Which study design would best answer this question?

Accepted Answer

Retrospective observational study comparing accident records of seat belt users and non-users

Types of Statistical Studies: Observational Studies, Experiments, and Study Design

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