Question 1

Which of the following best describes a confounding variable in an experiment?

Accepted Answer

An unknown variable that affects both the treatment and the response variable, making it difficult to determine causality.

Question 2

A researcher wants to test the effect of a new diet on weight loss. Participants are weighed before starting the diet and again after three months. What experimental design is being used?

Accepted Answer

Matched-pairs design

Question 3

Which of the following sampling techniques is most appropriate when the population is naturally divided into groups, and a random sample of groups is selected, with all individuals in chosen groups included in the sample?

Accepted Answer

Cluster sampling

Question 4

In a study, researchers want to ensure that each treatment group has similar numbers of males and females. Which technique should they use?

Accepted Answer

Blocking

Question 5

Which of the following is a potential source of bias in survey sampling?

Accepted Answer

Allowing voluntary participation

Question 6

Statistical power is defined as:

Accepted Answer

The probability of correctly rejecting the null hypothesis when it is false.

Question 7

Which formula correctly represents the calculation of statistical power?

Accepted Answer

$$	ext{Power} = 1 - \beta$$

Question 8

A researcher uses systematic sampling by selecting every 10th person from a list after a random start. Which of the following is a potential issue with this method?

Accepted Answer

It may introduce bias if there is a hidden pattern in the list.

Question 9

In a controlled experiment, what is the main advantage of random assignment of subjects to treatment groups?

Accepted Answer

It helps ensure that differences between groups are due to the treatment and not other factors.

Question 10

Which of the following best describes stratified sampling?

Accepted Answer

Dividing the population into subgroups based on a characteristic and randomly sampling from each subgroup.

Question 11

A study finds that people who eat at fast food restaurants are less likely to cook at home. If the sample only includes fast food customers, what type of bias is most likely present?

Accepted Answer

Selection bias

Question 12

Which of the following is NOT a way to avoid potential bias in sampling?

Accepted Answer

Voluntary participation

Question 13

Researchers want to study the effect of aerobic exercise on men's weights. To control for variability, they ensure each participant exercises the same number of minutes daily. What type of variability are they controlling?

Accepted Answer

Variability due to the amount of exercise

Question 14

Which of the following statements about observational studies is TRUE?

Accepted Answer

Subjects are observed without intervention, and assignment to groups is not controlled by the researcher.

Question 15

A researcher wants to estimate the average height of students at a university. Which sampling method would best ensure that students from all academic years are represented?

Accepted Answer

Stratified sampling

Question 16

Which of the following is a key feature of a crossover design?

Accepted Answer

Subjects receive multiple treatments in random order, with measurements taken after each treatment.

Question 17

Which of the following factors does NOT directly increase statistical power?

Accepted Answer

Increasing natural variability within the population

Question 18

Suppose a survey is conducted only among people who voluntarily choose to participate. What is the most likely problem with the results?

Accepted Answer

The results may not be representative of the population.

Question 19

Which of the following best describes the purpose of blocking in experimental design?

Accepted Answer

To reduce bias by ensuring each group is similar with respect to certain variables.

Question 20

If a sample mean is an unbiased estimator of the population mean, what does this imply?

Accepted Answer

The expected value of the sample mean equals the population mean.

Chapter 12

Guida di studio - Domande di pratica

Study guide - Flashcard