If there is sphericity in a repeated-measures design the outcome could be that
A) The p-value will be too high.
B) The p-value will be too low.
C) A p-value cannot be computed.
D) The p-value will not be related to the model

Question

Quizplus · Accepted Answer

Sphericity is the assumption that the variances of the differences between all possible pairs of related groups are equal. If sphericity is violated in a repeated-measures design, then the p-value computed with the standard ANOVA approach will be too low, leading to an increased risk of a Type I error (false positive). Therefore, a correction called the Greenhouse-Geisser correction or Huynh-Feldt correction should be applied to adjust the degrees of freedom and p-values.

If There Is Sphericity in a Repeated-Measures Design the Outcome