Question 1

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

Accepted Answer

A variable whose effects on the response variable cannot be distinguished from those of another variable.

Question 2

A pharmaceutical company wants to test a new drug. They divide participants into groups based on age (18–30, 31–50, 51+), then randomly assign each person within each age group to either the drug or placebo. What sampling technique is being used?

Accepted Answer

Stratified sampling

Question 3

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

Accepted Answer

Convenience

Question 4

A researcher wants to study the effect of a new teaching method. She randomly assigns students to either the new method or the traditional method, but neither the students nor the teachers know which method is being used. What is this experimental design called?

Accepted Answer

Double blind

Question 5

Which sampling technique is most likely to produce a biased sample?

Accepted Answer

Convenience sampling

Question 6

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

Accepted Answer

To provide a baseline for comparison by not receiving the treatment.

Question 7

A researcher uses a random number generator to select 50 students from a university’s enrollment list. Which sampling method is being used?

Accepted Answer

Simple random sampling

Question 8

Which of the following statements about the placebo effect is TRUE?

Accepted Answer

It occurs when subjects receive no treatment but believe they are receiving treatment and respond favorably.

Question 9

A researcher wants to study the effect of exercise on blood pressure. She pairs subjects based on age and gender, then randomly assigns one in each pair to the exercise group and the other to the control group. What type of experimental design is this?

Accepted Answer

Matched pairs design

Question 10

Which of the following best describes the Hawthorne effect?

Accepted Answer

Subjects change their behavior because they know they are being observed.

Question 11

A researcher selects every 10th person from a list of 1,000 employees to participate in a survey. What sampling method is this?

Accepted Answer

Systematic sampling

Question 12

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

Accepted Answer

A variable that affects the response variable but is not included in the study.

Question 13

Which of the following statements about variability is correct?

Accepted Answer

Variability is the degree of dispersion of data points in a distribution.

Question 14

A sample is drawn from a population using a method that gives every member an equal chance of being selected. What is this sampling method called?

Accepted Answer

Simple random sampling

Question 15

Which of the following best explains why replication is important in experimental design?

Accepted Answer

It helps confirm the accuracy and reliability of the original experiment’s results.

Question 16

A researcher wants to study the effect of a new fertilizer on plant growth. She divides the plants into groups based on soil type, then randomly assigns each plant within each group to either the new fertilizer or the standard fertilizer. What is this experimental design called?

Accepted Answer

Randomized block design

Question 17

Which of the following statements about sampling error is TRUE?

Accepted Answer

Sampling error is the difference between the results of a sample and those of the population.

Question 18

A researcher wants to study the effects of a new medication. She uses a mathematical model to simulate the effects on a virtual population. What type of data collection method is this?

Accepted Answer

Simulation

Question 19

Which of the following is a characteristic of a simple random sample?

Accepted Answer

Every possible sample of the same size has the same chance of being selected.

Question 20

Which of the following sampling methods involves dividing the population into naturally occurring groups, randomly selecting some groups, and including all members of those groups in the sample?

Accepted Answer

Cluster sampling

Data Collection and Experimental Design in Introductory Statistics

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