I have a basic questions on the interpretation of two different F contrasts
in a model
with 8 regressors (no.1-4: of no interest; no.5-8: "of interest"):
0 0 0 0 1 1 1 1
0 0 0 0 1
0 0 0 0 0 1
0 0 0 0 0 0 1
0 0 0 0 0 0 0 1
The questions on the regressors is/should be: are there brain areas
significantly associated with
any of the regressors?
In earlier postings explanations can be found stating that the hypothesis
in Contrast A is much
more restrictive than in B.
So my question is:
a. What is the more suitable contrast for the question mentioned?
b. If one of the regressors does not carry any weight, how much of a
"dilution" effect is present in the two contrasts?
c. What is the meaning of a region appearing in B but not A? (I think it
indicates that rather a single regressors brings in the effect, but I am
Thank you very much in advance for help in the interpretation here,
Max Planck Institute of Psychiatry
NMR Research Group
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