On 2/17/2020 6:51 AM, Star Xi wrote:

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Dear FS experts,
Hi!

I have a very basic question about GLM model in FS-FAST.

After GLM analysis, there is a beta.nii under the analysis/ directory and a ces.nii under each contrast/ directory.

In the tutorial, beta.nii is the regression coefficients and ces.nii is contrast effect size (contrast matrix * regression coef).

My question is :

1. both of them are regression coefficients, what’s the difference bewteen beta.nii and ces.nii.？

ces is a contrast of regresgression coefficients (ie, ces = C*beta where C is the contrast matrix), so they are related but not exactly the same thing

2. I want to do ROI analysis and extract the signal change in the given ROI from each individual. Which value represent the signal change (beta, ces, ceavar or t)?

either ces or beta. Usually you would make a contrast that embodies your hypothesis, then use the ces

Any suggestions are welcome!

Thanks

Star

Fudan University

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