Which statement best describes partitioning justification?

• A. At least 40 per subclass or clear clinical reasons
• B. At least 40 per subclass only
• C. Clear clinical reasons only
• D. Neither condition

Answer: (A)

When you split data into subgroups for analysis, you need enough observations in each subgroup so the results are stable and reliable. A common rule of thumb is at least 40 observations per subclass, which helps keep estimates precise and confidence intervals reasonable. If a particular subclass has fewer than that, you should not proceed blindly; instead, you should provide a clear clinical justification for studying that smaller group (for example, due to rarity or a specific, important hypothesis) rather than ignoring the data’s limitations. In short, partitioning justification means you either meet the numeric threshold in every subgroup or you have a solid clinical reason for why a subgroup can be studied with fewer observations.