Basic principles for all medical research MCQs With Answer

Introduction

Welcome to this focused quiz collection on the basic principles of medical research tailored for M.Pharm students. These multiple-choice questions are designed to reinforce essential concepts such as study design, bias and confounding, validity and reliability, hypothesis testing, sample size and power, ethical considerations, and interpretation of statistical results. Each question targets common examination topics and practical issues encountered during research planning, critical appraisal, and data analysis. Working through these MCQs will help you deepen conceptual understanding, recognize methodological pitfalls, and improve decision-making when designing or evaluating clinical and pharmacoepidemiological studies.

Q1. What is the primary purpose of randomization in a clinical trial?

• To ensure blinding of participants
• To eliminate all biases completely
• To distribute known and unknown confounders evenly between groups
• To increase the sample size

Correct Answer: To distribute known and unknown confounders evenly between groups

Q2. Which study design is most appropriate to estimate the incidence of a disease prospectively?

• Case-control study
• Cross-sectional study
• Cohort study
• Ecological study

Correct Answer: Cohort study

Q3. Which bias occurs when exposure or outcome information is collected differently for comparison groups?

• Selection bias
• Information bias
• Confounding bias
• Publication bias

Correct Answer: Information bias

Q4. In hypothesis testing, what does a Type I error represent?

• Failing to detect a real effect (false negative)
• Detecting an effect when there is none (false positive)
• Incorrect sample size calculation
• Misclassification of outcome

Correct Answer: Detecting an effect when there is none (false positive)

Q5. Which measure indicates the precision of an estimate and the range within which the true population value likely lies?

• p-value
• Confidence interval
• Effect modification
• Odds ratio

Correct Answer: Confidence interval

Q6. What is the main ethical requirement before enrolling participants in a clinical research study?

• Approval by the funding agency
• Publication plan in place
• Informed consent from participants
• Large sample size

Correct Answer: Informed consent from participants

Q7. Which statistical test is most appropriate to compare means of a continuous outcome between two independent groups with normally distributed data?

• Chi-square test
• Mann-Whitney U test
• Independent (unpaired) t-test
• Paired t-test

Correct Answer: Independent (unpaired) t-test

Q8. What does “intention-to-treat” analysis preserve in randomized controlled trials?

• Only the data from participants who completed the intervention per protocol
• Randomization-based group comparability by analyzing participants in their assigned groups
• The highest possible treatment effect estimate
• Removal of non-adherent participants to improve internal validity

Correct Answer: Randomization-based group comparability by analyzing participants in their assigned groups

Q9. Which factor does NOT directly increase statistical power of a study?

• Increasing sample size
• Increasing alpha level (e.g., from 0.01 to 0.05)
• Decreasing measurement variability
• Using a less sensitive outcome measure

Correct Answer: Using a less sensitive outcome measure

Q10. What is confounding?

• An error in measurement of exposure or outcome
• The effect modification by a third variable
• A distortion of the exposure-outcome relationship by a third variable associated with both
• A deliberate selection of participants

Correct Answer: A distortion of the exposure-outcome relationship by a third variable associated with both

Q11. Which term describes reproducibility of measurement when the same instrument yields similar results under consistent conditions?

• Validity
• Generalizability
• Reliability
• Sensitivity

Correct Answer: Reliability

Q12. Which outcome is considered a surrogate endpoint?

• All-cause mortality in a cardiovascular trial
• Blood pressure reduction as a proxy for stroke risk
• New symptomatic stroke events
• Quality-adjusted life years (QALYs)

Correct Answer: Blood pressure reduction as a proxy for stroke risk

Q13. When is a cross-sectional study design most useful?

• To establish temporal sequence and causality
• To measure prevalence of exposure and outcome at a single time point
• To follow participants over time to detect incidence
• To randomize exposures experimentally

Correct Answer: To measure prevalence of exposure and outcome at a single time point

Q14. Which method best reduces observer-expectancy bias in a clinical trial?

• Increasing sample size
• Blinding of outcome assessors
• Using non-random allocation
• Performing a cross-sectional analysis

Correct Answer: Blinding of outcome assessors

Q15. What does a p-value of 0.03 indicate in hypothesis testing?

• There is a 3% probability that the null hypothesis is true
• There is a 3% probability of observing the data, or more extreme, if the null hypothesis is true
• The alternative hypothesis is definitely true
• The result is not statistically significant at alpha = 0.05

Correct Answer: There is a 3% probability of observing the data, or more extreme, if the null hypothesis is true

Q16. Which sampling method is most likely to minimize selection bias for a community survey?

• Convenience sampling
• Simple random sampling from a defined population list
• Purposive sampling of volunteers
• Snowball sampling

Correct Answer: Simple random sampling from a defined population list

Q17. What is effect modification?

• When a confounder is controlled by stratification
• When the effect of the main exposure on the outcome differs across levels of a third variable
• When measurement error leads to bias toward the null
• When sample size is too small to detect an effect

Correct Answer: When the effect of the main exposure on the outcome differs across levels of a third variable

Q18. Which approach is correct for handling missing outcome data to avoid bias?

• Exclude all subjects with any missing data from analysis
• Use appropriate imputation methods and sensitivity analyses
• Replace missing values with group mean without further assessment
• Assume missing outcomes are all treatment failures

Correct Answer: Use appropriate imputation methods and sensitivity analyses

Q19. Which is the best description of external validity?

• The degree to which study results are free from systematic error
• The consistency of a measure across repeated tests
• The extent to which study findings can be generalized to other populations or settings
• The statistical significance of study findings

Correct Answer: The extent to which study findings can be generalized to other populations or settings

Q20. In planning a randomized controlled trial, which factor primarily determines the required sample size?

• Number of investigators
• Expected effect size, desired power, and acceptable alpha error
• Type of blinding used
• Study registration status

Correct Answer: Expected effect size, desired power, and acceptable alpha error

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