Quiz: QZ-20261001-88397

Quiz Details

QZ-20261001-88397

Topics:

Sample size derminantion for experimental designs

Difficulty: Level 5 - Very Hard

Questions: 14

Language: English (English)

Generated: October 01, 2026 at 03:27 PM

Generated by: Patience Juliet

Instructions: Select an answer for each question and click "Check Answer" to see if you're correct. Then view the explanation to learn more!

1 What is the primary purpose of determining sample size in experimental designs?

A) To simplify analysis

B) To increase variability

C) To ensure statistical significance

D) To reduce costs

Correct Answer: C
Explanation: Determining sample size is crucial to ensure that the study has enough power to detect a statistically significant effect if one exists.

2 Which of the following factors does NOT directly affect the required sample size?

A) Effect size

B) Researcher's experience

C) Power of the test

D) Alpha level

Correct Answer: B
Explanation: The researcher's experience does not directly influence the statistical calculations for sample size, while effect size, alpha level, and power are all critical components.

3 In a clinical trial aiming for a power of 0.80, what is the typical alpha level used?

A) 0.15

B) 0.05

C) 0.10

D) 0.01

Correct Answer: B
Explanation: A typical alpha level of 0.05 is used in clinical trials, meaning there is a 5% chance of making a Type I error.

4 When calculating sample size for comparing two means, what does 'effect size' represent?

A) The significance level

B) The difference between the means

C) The total sample size

D) The variance within each group

Correct Answer: B
Explanation: Effect size quantifies the magnitude of the difference between the means of two groups, which helps in determining the necessary sample size.

5 What is the relationship between sample size and confidence intervals?

A) Confidence intervals are only affected by standard deviation

B) Larger sample sizes lead to wider confidence intervals

C) Sample size does not affect confidence intervals

D) Larger sample sizes lead to narrower confidence intervals

Correct Answer: D
Explanation: As the sample size increases, the width of confidence intervals decreases, leading to more precise estimates of the population parameter.

6 For a one-tailed test, how does the required sample size compare to a two-tailed test at the same alpha level?

A) It requires a larger sample size

B) It depends on the effect size

C) It requires a smaller sample size

D) It requires the same sample size

Correct Answer: C
Explanation: A one-tailed test generally requires a smaller sample size than a two-tailed test because it focuses on detecting an effect in one direction only.

7 Which formula is commonly used for calculating sample size for comparing two proportions?

A) n = (Z^2 * (p1 + p2) * (1-p1 + 1-p2)) / E^2

B) n = (Z^2 * p * (1-p)) / E^2

C) n = (Z^2 * (p1 - p2)^2) / E^2

D) n = (Z^2 * (p1 + p2)) / E^2

Correct Answer: B
Explanation: The formula n = (Z^2 * p * (1-p)) / E^2 is used to determine the sample size needed to compare two proportions, where Z is the Z-value for the desired confidence level.

8 In power analysis, what does 'power' refer to?

A) The probability of accepting the null hypothesis when it is true

B) The probability of rejecting the null hypothesis when it is false

C) The effect size of the test

D) The likelihood of finding a significant result

Correct Answer: B
Explanation: Power is defined as the probability of correctly rejecting the null hypothesis when it is false, thus detecting an actual effect.

9 Which method is often used to estimate the sample size when the effect size is unknown?

A) Both A and B

B) Using a pilot study

C) Using a convenience sample

D) Using prior research findings

Correct Answer: A
Explanation: Estimating sample size when the effect size is unknown can be done by using previous research findings or conducting a pilot study to gather preliminary data.

10 What is the consequence of using an inadequate sample size in an experiment?

A) Increased risk of Type II error

B) Increased risk of Type I error

C) Increased reliability of results

D) No significant impact

Correct Answer: A
Explanation: An inadequate sample size may lead to an increased risk of Type II error, which is failing to detect a true effect due to insufficient power.

11 Which of the following is a common approach to determine sample size for longitudinal studies?

A) Cohort analysis

B) Repeated measures analysis

C) Meta-analysis

D) Cross-sectional analysis

Correct Answer: B
Explanation: Longitudinal studies often utilize repeated measures analysis to account for the same subjects being measured multiple times, impacting sample size calculations.

12 What factor might require an adjustment to the sample size calculation in studies involving human subjects?

A) Low variability

B) High dropout rates

C) Fixed effect size

D) Constant power level

Correct Answer: B
Explanation: High dropout rates necessitate an adjustment to the sample size to ensure that the final sample remains adequate for statistical analysis.

13 In stratified sampling, what is the main reason for determining sample size within each stratum?

A) To ensure equal representation

B) To increase sample size

C) To minimize cost

D) To maximize variance

Correct Answer: A
Explanation: Determining sample size within each stratum in stratified sampling ensures that each subgroup is adequately represented in the final sample.

14 When conducting a meta-analysis, what is a key consideration for sample size?

A) The size of the individual studies included

B) All of the above

C) The publication bias of the studies

D) The diversity of the study populations

Correct Answer: B
Explanation: In meta-analysis, all of the listed factors are important, as they influence the overall validity and generalizability of the combined results.

Want to generate another quiz?

Generate New Quiz Browse All Quizzes