I am using a mixed-Anova with one dependent variable measured across two time points (within-subject factor). There are two between-subject factors, between1 & between2, with items equally split across their respective levels.
Results indicate a significant within-subjects effect for the DV * between1, which is comprised of three groups: A, B, C.
Post hoc tests (Tukey's and Bonferroni) indicate significant effect for group A * group B:
However, plots of the estimated marginal means show a greater difference in slope steepness between group C (green) and the others, from time point 1 to time point 2:
Since I am measuring change in DV over time between these three groups, and if the plots are also representing this, then it seems there is a contradiction here.
If the slope of group C is so steep, then the DV has changed to a greater extent relative to groups A and B. If that is the case, given that the groups are all balanced, why would the post-hoc tests find a significant difference between groups A and B instead?
I guess I'm conceptually confused about something here, and it's probably a simple answer. Thanks in advance.