Clinical Trials and Statistical Analysis

Which of the following best minimises confounding in a randomised controlled trial?

• Increasing sample size

• Random allocation of participants

• Stratified analysis after data collection

• Matching cases and controls

A Type II error occurs when a researcher:

• Rejects a null hypothesis when it is true

• Fails to reject a null hypothesis when it is false

• Accepts an alternative hypothesis when it is false

• Concludes there is no bias when bias exists

The CONSORT flow diagram in clinical trials is primarily used to:

• Ensure blinding of investigators

• Track participant flow and attrition

• Standardise intervention protocols

• Compare baseline characteristics

Which of the following statistical tests is most appropriate for comparing the median length of hospital stay between two independent groups?

• Independent t-test

• Paired t-test

• Mann-Whitney U test

• Chi-square test

In survival analysis, the Kaplan-Meier method is primarily used to estimate:

• Hazard ratios

• Mean time to event

• Cumulative probability of survival over time

• Effect size of intervention

The 'power' of a study is defined as:

• Probability of correctly rejecting a true null hypothesis

• Probability of correctly rejecting a false null hypothesis

• Probability of avoiding a Type I error

• Ability of a test to measure what it is intended to measure

Which study design is most suitable for assessing the incidence of a disease?

• Cross-sectional study

• Case-control study

• Cohort study

• Ecological study

Which of the following distributions is most appropriate for analysing the number of adverse events per patient during a clinical trial?

• Normal distribution

• Poisson distribution

• Binomial distribution

• Chi-square distribution

Meta-analysis improves the precision of effect estimates primarily by:

• Eliminating publication bias

• Reducing heterogeneity

• Increasing effective sample size

• Adjusting for confounders

In regression analysis, multicollinearity is suspected when:

• P-value < 0.05

• Variance inflation factor (VIF) > 10

• R² < 0.5

• Residual plots are normally distributed