Hi Gang,
Thanks for the reply. Let me make sure with you about the interaction, and let's forget about the frequency just for simplicity:
my script was:
a1b1-a1b2-a2b1+a2b2
My understanding is: this is (a1b1-a1b2)-(a2b1-a2b2), it will contrast (b1-b2)'s differences in a1 and a2 condition, so that if there is any interaction effect, it will show.
Your suggestion was:
a1b1-a1b2-a2b1-a2b2
I don't understand why this would be the way to show interaction.
according to [
afni.nimh.nih.gov] , it seems my script was consistent with your previous post.
Can you elaborate a little bit?
Thank you!