Dear Experts,
I was wondering what can be a correct and accepted way to report an one-way between group ANOVA results.
Let's say we have 3 different groups. To assess if there is any difference between them, we performed an one-way ANOVA (F-contrast [1 -1 0; 0 1 -1]).
Here is my first question: is there a rule for thresholding this kind of analysis? Is a threshold of p=0.05 FWE too conservative?
Our results show a significant cluster (even with a p=0.05 FWE threshold). In order to know what is the direction of this effect, we used separated (3) between-groups two-sample t-tests. In order to be consistent, we used the same threshold.
Is that a good way to perform such an analysis?
Or would it be better, and less conservative, to use a different threshold, lest's say for exemple(and always trying to correct for multiple comparisons):
- F-test: p=0.0001 uncorrected and reporting only clusters with a significant peak with FWE correction
- post-hoc two-sample t-tests: p=0.0001 uncorrected at the voxel level but FWE corrected at the cluster level
Does it make sense? Is there any methodological issue?
Thanks for your comments/suggestions.
Cheers,
Yann
|