On Thu, 16 Dec 2004 16:50:31 +0100, Stefan Wiens <[log in to unmask]>
wrote:
>2.) Is it true that the 1st level t-contrasts test only for greater
activations before than after (ie pre minus post)? If one wanted to test
both tails (ie pre>post or post>pre), would it be correct to run F
contrasts on the first level and take these to the second level?
No, one runs t-tests at the first level and F-tests only at the second
level. See e.g.
http://www.jiscmail.ac.uk/cgi-bin/wa.exe?A2=ind0204&L=spm&P=R17492&I=-3
where Rik points out that one doesn't run an F-test at the first (i.e.,
subject) level and then bring the ess image to the second level.
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