What are post hoc tests?

What are post hoc tests?

• A. Tests used before ANOVA to check assumptions.
• B. Tests used to compare variances across groups.
• C. Post hoc tests are used after ANOVA to determine if any variances differ.
• D. Post hoc tests are used after ANOVA to determine which mean differences exist.

Answer: (D)

Post hoc tests are follow-up comparisons used after an ANOVA shows a significant difference among group means. The ANOVA tells you that at least one pair of group means differs, but it doesn’t say which pairs differ. Post hoc procedures examine the mean differences between groups and, importantly, adjust for the fact that many comparisons are being made, which helps control the familywise error rate. This lets you identify exactly which mean differences exist (for example, group A differs from group B, but group A and group C do not differ), using methods like Tukey’s HSD or Bonferroni. They are not used to check assumptions before ANOVA, nor are they about comparing variances across groups.

Post hoc tests are follow-up comparisons used after an ANOVA shows a significant difference among group means. The ANOVA tells you that at least one pair of group means differs, but it doesn’t say which pairs differ. Post hoc procedures examine the mean differences between groups and, importantly, adjust for the fact that many comparisons are being made, which helps control the familywise error rate. This lets you identify exactly which mean differences exist (for example, group A differs from group B, but group A and group C do not differ), using methods like Tukey’s HSD or Bonferroni. They are not used to check assumptions before ANOVA, nor are they about comparing variances across groups.