Designing research methodology and sample size determination MCQs With Answer

Designing research methodology and sample size determination are essential skills for B. Pharm students conducting clinical and pharmaceutical studies. This topic covers research design selection, hypothesis formulation, sampling techniques, validity and reliability, measurement error, and ethical considerations, plus statistical concepts like confidence intervals, power analysis, effect size, and margin of error. You’ll learn calculations for sample size in cross-sectional, cohort, case-control, and clinical trial designs, adjustments for cluster sampling and expected attrition, and use of software tools. Mastering these concepts improves study quality and patient safety. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. Which element primarily determines the minimum sample size required in hypothesis testing?

• Research question wording
• Significance level (alpha), power, and effect size
• Number of investigators
• Type of publication intended

Correct Answer: Significance level (alpha), power, and effect size

Q2. In sample size calculation for estimating a population proportion with specified precision, which parameter directly affects the required sample size most when prevalence is near 50%?

• Confidence level only
• Population size only
• Proportion (p) and its variability
• Number of study sites

Correct Answer: Proportion (p) and its variability

Q3. Power of a study is defined as:

• The probability of committing a Type I error
• The probability of detecting a true effect (1 – beta)
• The probability that results are clinically important
• The same as confidence level

Correct Answer: The probability of detecting a true effect (1 – beta)

Q4. Which sampling technique is most appropriate when the population is heterogeneous and you want to ensure representation from key subgroups?

• Simple random sampling
• Convenience sampling
• Stratified sampling
• Snowball sampling

Correct Answer: Stratified sampling

Q5. When designing a randomized clinical trial, what adjustment should you make in sample size calculation to account for expected dropouts?

• Subtract an estimated dropout percentage from calculated sample size
• Multiply calculated sample size by (1 – expected dropout rate)
• Increase the calculated sample size by dividing by (1 – expected dropout rate)
• No adjustment needed if randomization is used

Correct Answer: Increase the calculated sample size by dividing by (1 – expected dropout rate)

Q6. For cluster randomized trials, which factor inflates the sample size relative to an individually randomized trial?

• Smaller effect sizes
• Design effect due to intra-cluster correlation
• Lower alpha level
• Increased number of outcomes measured

Correct Answer: Design effect due to intra-cluster correlation

Q7. Which formula component is essential when estimating sample size for a continuous outcome comparing two independent means?

• Estimated standard deviation and desired effect size
• Estimated population proportion only
• Number of covariates in regression
• Type of blinding used

Correct Answer: Estimated standard deviation and desired effect size

Q8. In a cross-sectional prevalence study, increasing the desired precision (narrower margin of error) will:

• Decrease the required sample size
• Not change the sample size
• Increase the required sample size
• Affect only the confidence level

Correct Answer: Increase the required sample size

Q9. Which of the following is a correct reason to conduct a pilot study before the main trial?

• To publish preliminary results as the main outcome
• To estimate parameters like variance and refine procedures for sample size calculation
• To replace the main study if results are significant
• To avoid ethical approval for the main trial

Correct Answer: To estimate parameters like variance and refine procedures for sample size calculation

Q10. When calculating sample size for a case-control study aiming to detect an odds ratio, you need:

• Only the total population size
• Estimated exposure prevalence among controls and expected odds ratio
• Mean and standard deviation of continuous outcome
• Only the desired confidence interval width

Correct Answer: Estimated exposure prevalence among controls and expected odds ratio

Q11. The finite population correction factor becomes important when:

• The population is very large relative to sample
• The sample size is a substantial fraction (>5–10%) of the total population
• Only for case-control studies
• When using stratified randomization

Correct Answer: The sample size is a substantial fraction (>5–10%) of the total population

Q12. Which is true about one-sided versus two-sided hypothesis tests in sample size planning?

• One-sided tests require larger sample sizes than two-sided tests for the same effect
• Two-sided tests are more conservative and usually need larger sample sizes than one-sided tests
• They always require the same sample size
• Choice does not affect sample size calculation

Correct Answer: Two-sided tests are more conservative and usually need larger sample sizes than one-sided tests

Q13. What is the effect size in sample size determination?

• The sample proportion only
• The magnitude of difference or association the study aims to detect
• The number of variables measured
• The p-value threshold

Correct Answer: The magnitude of difference or association the study aims to detect

Q14. Which software is commonly used for sample size and power calculations in biomedical research?

• Photoshop
• G*Power
• Microsoft Word
• AutoCAD

Correct Answer: G*Power

Q15. If you reduce the Type I error rate (alpha) from 0.05 to 0.01 while keeping other parameters constant, the required sample size will generally:

• Decrease
• Increase
• Remain unchanged
• Become zero

Correct Answer: Increase

Q16. Which sampling method is most prone to selection bias and least likely to be representative?

• Probability sampling
• Systematic random sampling
• Convenience sampling
• Stratified random sampling

Correct Answer: Convenience sampling

Q17. In paired or crossover designs, required sample size compared to independent designs is usually:

• Smaller because paired designs reduce variability
• Larger because of carryover effects
• Always the same
• Independent of effect size

Correct Answer: Smaller because paired designs reduce variability

Q18. What does intra-cluster correlation coefficient (ICC) measure in clustered samples?

• The number of clusters needed
• The similarity of outcomes within the same cluster
• The dropout rate in trials
• The effect size magnitude

Correct Answer: The similarity of outcomes within the same cluster

Q19. Which approach is appropriate to adjust sample size for multiple comparisons to control family-wise error rate?

• Ignore multiple testing
• Use Bonferroni or other correction methods
• Decrease power arbitrarily
• Only report unadjusted p-values

Correct Answer: Use Bonferroni or other correction methods

Q20. For a prevalence study of a rare event (<5%), to achieve a given precision, compared to a common event, the required sample size is typically:

• Smaller
• Larger
• Exactly the same
• Dependent only on confidence level

Correct Answer: Larger

Q21. External validity (generalizability) is most influenced by:

• Statistical significance only
• Sampling method and representativeness of the sample
• Number of variables measured
• Use of advanced statistical software

Correct Answer: Sampling method and representativeness of the sample

Q22. When planning a superiority trial, non-inferiority margin is:

• Always equal to zero
• Not relevant; it applies to non-inferiority trials
• Used to detect harm only
• Determined by the number of endpoints

Correct Answer: Not relevant; it applies to non-inferiority trials

Q23. Which factor should be estimated from previous studies or pilot data when calculating sample size for continuous outcomes?

• Loss to follow-up only
• Standard deviation of the outcome
• Number of research assistants
• Journal impact factor

Correct Answer: Standard deviation of the outcome

Q24. In sample size estimation for time-to-event (survival) analysis, what additional element is commonly required?

• Assumed event rate and total follow-up time
• Only baseline prevalence
• Number of clusters only
• Type of randomization

Correct Answer: Assumed event rate and total follow-up time

Q25. Which is a valid reason to increase sample size beyond the minimum statistical requirement?

• To ensure adequate subgroup analyses and regulatory expectations
• To make data analysis more complex
• To reduce the need for ethical approval
• To guarantee a significant p-value

Correct Answer: To ensure adequate subgroup analyses and regulatory expectations

Q26. Reliability of a measurement tool affects sample size because:

• Higher measurement error increases variability, often requiring larger samples
• Reliability has no influence on sample size
• More reliable tools always require larger samples
• Reliability is only relevant for qualitative studies

Correct Answer: Higher measurement error increases variability, often requiring larger samples

Q27. When planning stratified sampling, how should sample size allocation be done for proportional allocation?

• Allocate equal numbers to each stratum regardless of size
• Allocate samples proportional to stratum sizes
• Allocate all samples to the largest stratum
• Ignore stratification in sample size

Correct Answer: Allocate samples proportional to stratum sizes

Q28. Which ethical consideration is directly tied to accurate sample size determination?

• Reducing participant burden by enrolling an unnecessary large sample
• Maximizing funding use regardless of participants
• Avoiding underpowered studies that expose participants without benefit
• Recruiting only from convenient populations

Correct Answer: Avoiding underpowered studies that expose participants without benefit

Q29. What is the primary purpose of using confidence intervals alongside sample size planning?

• To provide a range of plausible values for the population parameter and reflect precision
• To replace hypothesis testing
• To determine study funding
• To decide the number of investigators

Correct Answer: To provide a range of plausible values for the population parameter and reflect precision

Q30. If a study measures multiple correlated outcomes, what is a recommended approach during sample size planning?

• Calculate sample size based on the single most important outcome and consider multiplicity adjustments
• Ignore correlation and treat outcomes as independent always
• Reduce sample size because correlation lowers variance
• Randomly choose one outcome after data collection

Correct Answer: Calculate sample size based on the single most important outcome and consider multiplicity adjustments

Download