Subgroup analyses are used to identify what?

• A. Identify high- and low-risk groups; guide targeted interventions
• B. Increase sample size
• C. Equalize baseline characteristics
• D. Reduce measurement error

Answer: (A)

Subgroup analyses examine whether the effect of an exposure or intervention differs across predefined groups of participants. This approach helps reveal which groups are at higher or lower risk and how they respond differently, which in turn informs targeted interventions. For example, if a treatment works better in younger patients or those with a higher baseline risk, you can prioritize resources for those groups. The other options miss the primary purpose: increasing sample size is achieved by enrolling more participants or combining data, not by analyzing subgroups; randomization or stratification is used to balance baseline characteristics, not the analysis per se; and measurement error relates to data quality, not identifying differential risk across groups.