Psych 318 Repeated-measures ANOVA (Chapter 14)
In a one-way repeated-measures design, we are back to one independent variable with k levels. The number of
observations at each level is the same because we are either using the same subjects in each condition (level) or we
have matched our subjects on some third variable and have randomly assigned yoked subjects to conditions.
There is one primary statistical analysis in a one-way repeated-measures design.
Test of the effect of the IV
F = SSA/dfA/SSerror/dferror
dfA = a-1
SSA is based on deviations of the A marginal means
from the grand mean
The error term (MSerror) however, is NOT the pooled variances of the groups. SSerror is based on the SS that remains
when the SSsubjects and SStreat has been removed from SStotal. The dferror = (n-1)(k-1).
SStreat is computed the same way that it was computed in the one-way between subjects design (see above).
What is SSsubjects ?
SSsubjects is based on the deviations of each of the subjects’ overall mean from the grand mean.
One way to conceptualize this is to think of each subject as a row (level) of a variable called “subject.”
Although SSsubject is computed, “subjects” is not a factor we have any interest in testing.
There are secondary analyses that may be carried out in a one-way repeated-measures design, and these consist of1.
comparisons among the group means when k>2.