I forgot to include all relevant contrasts in FEAT analyses already run. Rerunning all analyses will take a lot of time. Is there a way to avoid this, by simply calculating these contrasts from activation-vs-baseline contrasts I already got from my analyses?
For example, I would like to calculate contrast C from the available activation-vs-baseline contrasts A and B:
_ ev1 ev2
A 1 0
B 0 1
C -1 1 (not available in analysis)
Is there a simple formula which can be used at higher level to calculate the zstat for contrast C based on available cope/pe/zstat data from contrasts A and B? Or is the only solution to re-run all the analyses?
Thanks in advance for your reply!
Henk van Steenbergen
Leiden Institute for Brain and Cognition, The Netherlands