Hi Julian,

Could you tell the following:

- How are the correlations between baseline and follow-up computed? Do you do some kind of spatial correlation between results, or do you check whether task-based BOLD-responses are correlated in both scans? Or something else?
- How are the groups defined? Is this a randomized controlled trial or just an observational study of the kind patients vs. controls?

All the best,

Anderson


On Fri, 24 May 2019 at 12:50, Julian Macoveanu <[log in to unmask]> wrote:
Hi all,

I have 2 groups scanned with fMRI twice. Due to the known high within subject variability which approaches between-subject values, my group decided to first perform a correlation test between baseline and follow-up measurements. If there is a significant correlation between baseline & follow-up then we would like to perform a 2-sample t-test using the follow-up data while adjusting for baseline data. If the correlation test is negative i.e. the baseline cannot predict the follow-up, then we would just do the 2-sample follow-up t-test without baseline correction. Instead we would simply check that whatever we find between groups at follow-up was not present between groups at baseline.

Now, the question is, do you think this is a sensible approach? Can the correlation analysis be made in FEAT somehow using voxelwise covariates? I guess if I find the answer to this question I can also move on and similarly adjust the data by the baseline data as covariate.

Julian


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