Study design and types of studies MCQs With Answer

Introduction: Study design and types of studies are central to conducting rigorous research in pharmaceutical sciences. This MCQ set is designed for M.Pharm students to deepen understanding of experimental and observational study designs, their strengths, limitations, bias sources, and implications for data interpretation. Questions focus on randomized controlled trials, cohort and case-control studies, cross-sectional surveys, quasi-experimental approaches, diagnostic accuracy studies, and specialized designs such as crossover, factorial, cluster-randomized and non-inferiority trials. Emphasis is placed on practical issues like prospective vs retrospective timing, blinding, allocation concealment, intention-to-treat analysis, and selection of appropriate endpoints—key concepts for designing, appraising and conducting high-quality pharmacoepidemiological and clinical research.

Q1. Which study design is best suited to estimate incidence of a disease and assess temporal sequence between exposure and outcome?

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

Correct Answer: Cohort study

Q2. Which of the following is the main advantage of a randomized controlled trial (RCT) over observational designs?

• Lower cost and faster completion
• Ability to estimate prevalence
• Reduction of confounding through randomization
• Better external validity for population-level estimates

Correct Answer: Reduction of confounding through randomization

Q3. In a case-control study the primary measure of association is:

• Incidence rate
• Risk difference
• Odds ratio
• Cumulative incidence

Correct Answer: Odds ratio

Q4. Which design is retrospective by definition and most efficient for studying rare outcomes?

• Prospective cohort study
• Randomized controlled trial
• Case-control study
• Cross-sectional survey

Correct Answer: Case-control study

Q5. A crossover trial is particularly useful when:

• The outcome is irreversible
• There is a long carry-over effect of the intervention
• Within-subject comparisons are desired and condition is stable
• Cluster-level interventions are required

Correct Answer: Within-subject comparisons are desired and condition is stable

Q6. Which term describes a study that assigns interventions but lacks random allocation?

• Randomized controlled trial
• Quasi-experimental study
• Prospective cohort study
• Case series

Correct Answer: Quasi-experimental study

Q7. Which study design is most appropriate to evaluate diagnostic test accuracy against a gold standard?

• Ecological study
• Diagnostic cross-sectional study (consecutive patients with index test and reference standard)
• Randomized controlled trial
• Case-control study of cases and healthy controls

Correct Answer: Diagnostic cross-sectional study (consecutive patients with index test and reference standard)

Q8. Which bias is minimized by allocation concealment in randomized trials?

• Observer-expectancy bias
• Selection bias due to foreknowledge of treatment assignment
• Performance bias from lack of blinding
• Publication bias

Correct Answer: Selection bias due to foreknowledge of treatment assignment

Q9. Intention-to-treat (ITT) analysis primarily preserves which feature of randomized trials?

• Per-protocol efficacy estimation
• Balance of prognostic factors achieved by randomization
• Minimization of measurement error
• Reduction of observer bias

Correct Answer: Balance of prognostic factors achieved by randomization

Q10. A cluster randomized trial randomizes which unit?

• Individual participant only
• Treatment allocation by outcome status
• Groups such as clinics, communities, or schools
• Time periods rather than participants

Correct Answer: Groups such as clinics, communities, or schools

Q11. In an equivalence or non-inferiority trial, choice of the non-inferiority margin primarily affects:

• Blinding procedures
• Ethical approval processes
• Interpretation of whether a new treatment is acceptably close to standard
• Randomization stratification factors

Correct Answer: Interpretation of whether a new treatment is acceptably close to standard

Q12. Which study design is most vulnerable to ecological fallacy when inferences about individuals are drawn from group-level data?

• Case series
• Cross-sectional study
• Ecological study
• Prospective cohort study

Correct Answer: Ecological study

Q13. Which is a key characteristic of a prospective study design?

• Exposure and outcome are assessed at a single point in time
• Outcomes are assessed after exposures are recorded and participants are followed forward
• Exposure is reconstructed from past records only
• Only prevalent cases are included

Correct Answer: Outcomes are assessed after exposures are recorded and participants are followed forward

Q14. Which design is primarily descriptive and useful for hypothesis generation rather than hypothesis testing?

• Randomized controlled trial
• Case report or case series
• Case-control analytic study
• Diagnostic cohort

Correct Answer: Case report or case series

Q15. What is the main purpose of stratified randomization in clinical trials?

• To blind participants to treatment allocation
• To ensure balance of important prognostic factors across treatment arms
• To increase external validity of the study
• To reduce sample size requirements

Correct Answer: To ensure balance of important prognostic factors across treatment arms

Q16. Which study design allows simultaneous examination of multiple exposures in relation to a single outcome and is efficient for rare diseases?

• Cross-over randomized trial
• Case-control study
• Cohort study
• Cross-sectional survey

Correct Answer: Case-control study

Q17. In longitudinal cohort studies, loss to follow-up most threatens which type of validity?

• Construct validity
• Internal validity through selection bias
• Content validity
• Face validity

Correct Answer: Internal validity through selection bias

Q18. A factorial trial design is best used when investigators want to:

• Randomize clusters instead of individuals
• Test the effects of two or more interventions and their interactions in the same trial
• Ensure each participant receives both interventions sequentially
• Prevent carry-over effects between treatments

Correct Answer: Test the effects of two or more interventions and their interactions in the same trial

Q19. Which option correctly differentiates cross-sectional and case-control studies?

• Cross-sectional studies are retrospective and case-control are prospective
• Cross-sectional measure exposure and outcome at one time; case-control select participants by outcome status and look back for exposures
• Case-control studies measure prevalence; cross-sectional studies estimate odds ratios only
• Both designs always provide incidence estimates

Correct Answer: Cross-sectional measure exposure and outcome at one time; case-control select participants by outcome status and look back for exposures

Q20. When selecting a surrogate endpoint for a trial, the most important consideration is:

• Ease of measurement regardless of clinical relevance
• Whether the surrogate is strongly and consistently correlated with the true clinical outcome and lies on the causal pathway
• That the surrogate has high prevalence in the study population
• That surrogate outcomes allow open-label designs

Correct Answer: Whether the surrogate is strongly and consistently correlated with the true clinical outcome and lies on the causal pathway

Download