Hi - no, you expect this:   -1 x -1 = 1

Cheers, Steve.

On 11 Jun 2013, at 05:11, Maryam Abaei <[log in to unmask]> wrote:

Dear FSL experts,

I have run seed-based analysis, using Feat. For lower level, I had 8 confounds (WM, CSF and 6 motion parameters) and I had two contrasts for positive and negative correlation:

c1: 1 00 00 00 00

c2:  -1 00 00 00 00

Then for higher level analysis I had two groups with 4 contrast:

C1: A>B

C2: B>A

C3: Mean A

C4: Mean B

The higher level results for two contrasts (c1 and c2) are exactly the same just swap between C1 and C2. For example, C1 with positive correlation (c1) has the same cluster as C2 with negative correlation (c2).

I am wondering if anything was wrong in my design matrix/contrast?

Best wishes,

Maryam

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Stephen M. Smith, Professor of Biomedical Engineering
Associate Director,  Oxford University FMRIB Centre

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