There are no negative clusters in abs.

I tried to apply the permutation but it says it requires an orthogonal matrix.

Right now I am using this:

-1 1 0 0

How would my orthogonal matrix look like?

Thanks,

Vale

________________________________ From: freesurfer-bounces@nmr.mgh.harvard.edu freesurfer-bounces@nmr.mgh.harvard.edu on behalf of Greve, Douglas N.,Ph.D. DGREVE@mgh.harvard.edu Sent: Thursday, February 14, 2019 12:14:27 PM To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] GLM - correction for multiple comparisons

It is certainly possible. Are some of the clusters in abs negative? Also, I would strongly recommend using permutation if you are using such a low clusterwise threshold. See https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/MultipleComparisonsV6.0... The monte carlo simulation is not valid at such low thresholds

On 2/14/19 11:50 AM, Barletta, Valeria wrote:

Dear Freesurfers,

I am performing a GLM analysis on two groups (patients versus controls) and one variable (age).

We are using the following option to correct for multiple comparisons:

mri_glmfit-sim --glmdir ${glm_dir}/${hemi}_contrast-${contrast}_${surfname_t1} --cache 1.3 pos/abs

Is it normal to have those 2 different results when using pos or abs option? (see screenshots)

Thank you!

Vale

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