When several subgroups are compared in a study, what is the rule of thumb about the sample or subsample size?
A) At least 100 participants in the study is needed.
B) At least 50 participants in the study is needed.
C) At least 30 participants in each subgroup is needed.
D) At least 15 participants in each subgroup is needed.

Question

Quizplus · Accepted Answer

The rule of thumb is to have at least 30 participants in each subgroup. This ensures adequate statistical power to detect differences between groups and reduces the likelihood of Type II errors. Having fewer than 30 participants in a subgroup can increase the risk of a Type II error, where a difference between groups exists but is not detected due to low sample size. Therefore, choice C is the best option.

When Several Subgroups Are Compared in a Study, What Is