Question 1

Which of the following best describes the difference between a population and a sample in statistics?

Accepted Answer

A population includes all subjects of interest, while a sample is a subset of the population.

Question 2

A researcher wants to study the effect of a new drug on blood pressure. She randomly assigns 100 patients to receive either the new drug or a placebo and measures their blood pressure after 6 weeks. What type of study is this?

Accepted Answer

Experiment

Question 3

Which of the following is a key advantage of an experiment over an observational study?

Accepted Answer

Experiments can establish cause and effect relationships.

Question 4

In a study investigating the relationship between cell phone use (in hours per day) and the development of brain tumors, which is the explanatory variable?

Accepted Answer

Cell phone use (hours per day)

Question 5

A sample survey is conducted by interviewing people at a local mall to estimate the average income of residents in a city. What is the most likely source of bias in this study?

Accepted Answer

Sampling bias due to convenience sampling

Question 6

Which of the following best describes a simple random sample (SRS)?

Accepted Answer

A sample where each possible sample of the same size has an equal chance of being selected.

Question 7

Suppose a survey reports a margin of error of ±4%. If the sample estimate for support of a policy is 60%, what is the likely range for the true population percentage?

Accepted Answer

$$56\% to$$ $$64\%$$

Question 8

Which of the following is NOT a component of a well-designed experiment?

Accepted Answer

Convenience sampling

Question 9

A double-blinded experiment is one in which:

Accepted Answer

Neither the subjects nor the researchers know which treatment each subject receives.

Question 10

A study finds that moderate alcohol consumption is associated with a lower risk of type II diabetes, but the study is observational. Which of the following is a valid conclusion?

Accepted Answer

There is an association between moderate alcohol consumption and lower risk of type II diabetes.

Question 11

Which formula gives a rough approximation for the margin of error in a simple random sample of size $$n$$?

Accepted Answer

$$\frac{1}{\sqrt{n}}$$

Question 12

A researcher uses a volunteer sample to study exercise habits. What is a likely problem with this sampling method?

Accepted Answer

Volunteers may not be representative of the population.

Question 13

Which of the following is an example of response bias?

Accepted Answer

The survey question is worded in a way that leads people to a particular answer.

Question 14

In an experiment, what is the purpose of randomization?

Accepted Answer

To eliminate bias and balance groups on known and unknown variables.

Question 15

A clinical trial compares a new medication to an existing one. What is the role of the control group in this experiment?

Accepted Answer

To allow comparison and measure the effectiveness of the new medication.

Question 16

Which of the following statements about statistical significance is correct?

Accepted Answer

A result is statistically significant if it is larger than what would be expected by chance alone.

Question 17

A researcher wants to generalize the results of a study to a larger population. What is a necessary condition for this generalization to be valid?

Accepted Answer

The sample must be representative of the population.

Question 18

Which of the following is an example of a lurking variable in a study of the relationship between exercise and heart disease?

Accepted Answer

Diet, which may affect both exercise habits and heart disease risk

Question 19

A study uses a table of random numbers to select a sample. What is the main benefit of this approach?

Accepted Answer

It ensures that every possible sample has an equal chance of being selected.

Question 20

Which of the following best describes the placebo effect?

Accepted Answer

An improvement in health due to the patient’s belief in the treatment, not the treatment itself.

Study Design and Data Gathering in Introductory Statistics

Study Guide - Practice Questions

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