Why are subgroup analyses at risk of spurious findings, and how can you mitigate this risk?

Why are subgroup analyses at risk of spurious findings, and how can you mitigate this risk?

• A. Multiple comparisons create false positives; pre-specify subgroups and adjust for multiplicity or treat analyses as exploratory
• B. Subgroup analyses always produce accurate results
• C. Subgroup analyses reduce study power; not necessary to pre-specify
• D. Subgroup analyses are never biased

Answer: (A)