Question 1

Which of the following best describes a simple random sample?

Accepted Answer

A sample in which every possible sample of the same size has the same chance of being chosen.

Question 2

A pharmaceutical company wants to test a new drug. They randomly assign patients to either receive the drug or a placebo, and neither the patients nor the administering doctors know who receives which. What type of experimental design is this?

Accepted Answer

Double-blind experiment

Question 3

Which sampling method is illustrated by selecting every 5th car that passes a checkpoint?

Accepted Answer

Systematic sampling

Question 4

A researcher divides a city into neighborhoods, randomly selects three neighborhoods, and surveys every household in those neighborhoods. What sampling method is this?

Accepted Answer

Cluster sampling

Question 5

Which of the following is an example of a lurking variable?

Accepted Answer

Temperature affecting both ice cream sales and drowning rates

Question 6

In a study, researchers observe and record the eating habits of participants without intervening. What type of study is this?

Accepted Answer

Observational study

Question 7

Which of the following best describes a retrospective study?

Accepted Answer

Data are collected from a past time period by going back in time.

Question 8

A researcher wants to compare the effectiveness of two diets. She matches participants in pairs based on age and weight, then randomly assigns one from each pair to each diet. What design is this?

Accepted Answer

Matched pairs design

Question 9

Which of the following is a source of nonsampling error?

Accepted Answer

Entering incorrect data into a spreadsheet

Question 10

A pollster divides the population into men and women, then randomly selects individuals from each group. What sampling method is this?

Accepted Answer

Stratified sampling

Question 11

Which of the following best describes the placebo effect?

Accepted Answer

An untreated subject reports improvement in symptoms due to believing they are treated.

Question 12

Which of the following is an example of convenience sampling?

Accepted Answer

Surveying people who are easy to reach, such as those walking by in a mall

Question 13

A study collects data from a group of patients at a single point in time. What type of observational study is this?

Accepted Answer

Cross-sectional study

Question 14

Which of the following is a key advantage of randomization in experiments?

Accepted Answer

It helps create groups that are similar, reducing bias.

Question 15

A researcher uses a combination of stratified and cluster sampling in different stages of a survey. What is this method called?

Accepted Answer

Multistage sampling

Question 16

Which of the following is an example of a sampling error?

Accepted Answer

A sample mean differs from the population mean due to chance.

Question 17

In a randomized block design, what is the purpose of forming blocks?

Accepted Answer

To group subjects with similar characteristics that might affect the outcome.

Question 18

Which of the following best describes confounding in an experiment?

Accepted Answer

An effect is observed, but the specific factor causing it cannot be identified.

Question 19

A researcher assigns subjects to treatment groups so that each group is similar in important ways, but does not use randomization. What is this design called?

Accepted Answer

Rigorously controlled design

Question 20

Which of the following is a nonrandom sampling error?

Accepted Answer

Using a convenience sample instead of a random sample

Introduction to Statistics: Key Concepts and Methods

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