CPI Study Design & Methodology 2 — Questions and Answers
Question 1: A researcher wants to determine whether a new drug causes fewer side effects than the standard treatment. Which study design provides the strongest causal evidence?
- Cross-sectional survey
- Randomized controlled trial (Correct answer)
- Case-control study
- Ecological study
Correct answer: Randomized controlled trial
Randomized controlled trials randomly assign participants to treatment groups, minimizing confounding and providing the strongest causal evidence.
Question 2: In a factorial design, a researcher tests two drugs (A and B) each at two doses (high and low). How many treatment conditions exist?
- 2
- 4 (Correct answer)
- 6
- 8
Correct answer: 4
A 2×2 factorial design creates 4 conditions: A-high, A-low, B-high, and B-low, allowing analysis of main effects and interactions.
Question 3: Which sampling method divides a population into subgroups and randomly selects participants from each subgroup proportionally?
- Cluster sampling
- Convenience sampling
- Stratified random sampling (Correct answer)
- Systematic sampling
Correct answer: Stratified random sampling
Stratified random sampling divides the population into strata and samples proportionally from each, improving representativeness.
Question 4: A study enrolls participants based on their disease status and then looks back to identify past exposures. This is best described as:
- Prospective cohort study
- Case-control study (Correct answer)
- Cross-sectional study
- Randomized trial
Correct answer: Case-control study
Case-control studies select participants based on outcome (cases vs. controls) and retrospectively assess prior exposures.
Question 5: When a researcher measures the same variable using two different instruments and compares results, they are assessing:
- Internal consistency
- Convergent validity (Correct answer)
- Face validity
- Criterion validity
Correct answer: Convergent validity
Convergent validity is demonstrated when two measures of the same construct produce similar results.
Question 6: Which principle in research design ensures that neither the participant nor the investigator assessing outcomes knows the treatment assignment?
- Blinding (Correct answer)
- Randomization
- Allocation concealment
- Stratification
Correct answer: Blinding
Double-blinding ensures neither participants nor outcome assessors know treatment assignments, reducing performance and detection bias.
Question 7: A researcher studies disease prevalence and risk factors at a single point in time across a defined population. This design is called:
- Longitudinal study
- Case series
- Cross-sectional study (Correct answer)
- Cohort study
Correct answer: Cross-sectional study
Cross-sectional studies collect data at one time point, measuring prevalence and associations but not establishing temporality.
CPI Study Design & Methodology 2
A researcher wants to determine whether a new drug causes fewer side effects than the standard treatment.
Which study design provides the strongest causal evidence?