You need more subjects. There are various journal articles that discuss the "required" number.
Chris
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From: SPM (Statistical Parametric Mapping) [[log in to unmask]] on behalf of fMRI [[log in to unmask]]
Sent: Friday, July 12, 2013 11:51 AM
To: [log in to unmask]
Subject: [SPM] Number of subjects
Hi all,
I scanned five people. I then did the second level specifications. I took contrast images ( con_0001*) an entered them into a simple t test.
My question is : in the first level, I got a very high activations in where I was expected and with FWE. In the second level, I do not get any FWE but get uncorrected although small in size.
I thought this may be due to either the number of subjects or something went wrong in the second level.
So how many subject on average an fmri study should have?
In the second level, is it correct if I smooth the contrast again? I have done this.
In the second level, i keep the default and just enter the images
Regards,
AS
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