I have a 2 (time) x 3 (levels of difficulty) repeated measures design. My repeated measures ANOVA yielded a significant main effect of time, but no interaction. From this I can claim that there is a significant difference at each time point for all 3 levels of difficulty.
However, if I peek at the simple main effect (e.g., level 1 difficulty at each time) using a paired t test, the difference is non-significant at the .05 level (but is close). I know I am not supposed to do this, but can someone please explain how there can be a significant main effect, but non-significant simple main effects?