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Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

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The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Kosuke
April 20, 2020 04:48AM
Hello,

I have been trying to test a difference of covariate effect between two groups. I got stat for that labeled "GroupA-GoupB_cov1_Tstat" using 3dttest++ as follows: 

3dttest++ \
    -setA   GroupA \
        A01     beta.nii.gz \
        A02     beta.nii.gz \
        A03     beta.nii.gz \
        A04     beta.nii.gz \
    -setB   GroupB \
        B01     beta.nii.gz \
        B02     beta.nii.gz \
        B03     beta.nii.gz \
    -covariate \
        cov.txt

where 'cov.txt' is something like that: 

name    cov1
A01       -4
A02      -22
A03       -6
A04       32
B01       32
B02      -28
B03       -4

Values of "cov1" were manually centered within each group.

How can we get the same stat using 3dMEMA? I tried like below, but a result looked different from that of 3dttest++. Is this a matter of coding covariates? 

3dMEMA \
    -groups GroupA GroupB \
    -set    GroupA \
        A01     beta.nii.gz    tstat.nii.gz \
        A02     beta.nii.gz    tstat.nii.gz \
        A03     beta.nii.gz    tstat.nii.gz \
        A04     beta.nii.gz    tstat.nii.gz \
    -set    GroupB \
        B01     beta.nii.gz    tstat.nii.gz \
        B02     beta.nii.gz    tstat.nii.gz \
        B03     beta.nii.gz    tstat.nii.gz \
    -covariate          cov.txt \
    -covariate_center   cov1 = 0 0

Thanks,

Kosuke
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Subject Author Posted

Covariate interaction in two-sample 3dMEMA

Kosuke April 20, 2020 04:48AM

Re: Covariate interaction in two-sample 3dMEMA

gang April 20, 2020 09:47AM

Re: Covariate interaction in two-sample 3dMEMA

Kosuke April 21, 2020 03:32PM