Dear all,
I have read many useful messages regarding rfx masking issues in the
archives, but as there are a number of options described for doing this (and
most apply to between-groups analyses), I wondered what the current (SPM2)
preferred method would be for the following:
I want to take 2 contrasts per subject (A > baseline; B > baseline)
to the 2nd level and then mask them exclusively in order to assess significant
within-group (Basic Models 1-sample t-tests) activations exclusive to A >
baseline/B > baseline.
a) Is there a consensus as to the best way of doing it?
b) Is THIS one correct way of doing it?: Do 2nd-level contrasts (A
> baseline; B > baseline) and use ImCalc with this function (i1-1).*(-1)
to produce exclusive masks at the p-threshold chosen in displaying the
contrasts. Use these masks in the "explicit masking" option when estimating
A > baseline (use B > baseline mask) and B > baseline (use A >
baseline mask).
Many thanks and best wishes,
Tobias Egner
