Interaction effect but no simple effects?

Hi All,

I have conducted a two-way within-subject repeated measures ANOVA, examining a dependent variable over 5 time-points under 2 conditions. An interaction effect is revealed but when I proceed to examine the simple effects using one-way ANOVAs there are no significant effects. I am not a statistician by all means so do not know how to interpret and explain this. Any help would be greatly appreciated.

Thank you in advance!


Well-Known Member
Have you tried plotting the two conditions on the same graph over the 5 time periods? It might explain everything.
Probably the general level of the data stays much the same over time but the pattern of deviations from that general level may be quite different.