Hi,
I presume you mean if you "double" the data at first level.
Yes - it is not the t that is passed up, it is the B in your equation,
so if you double Y and hold X fixed then B will double, and this will
change the second-level analysis.
This is why in FEAT preprocessing each session's data is "grand-mean-
intensity-normalised" to have a fixed mean intensity inside the
brain. If you rescale your data before feeding into FEAT then this
will get removed by this process.
Cheers.
On 5 Mar 2009, at 22:08, Yunjie Tong wrote:
> Hi FSL users,
>
> I have a question about the second level analysis in FSL. Say if I
> double the detected signal in one subject, I will end up with the
> same t value on the first level analysis due to the fact that both
> the B and error are doubled ( Y=XB+error). Is that going to affect
> my (second level) group analysis? Thanks.
>
> Bests,
>
> YJ
>
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