Dear Prof Smith
We have some DTI data that we’ve processed for TBSS analysis. We have
generated design matrix and contrast files for the subsequent voxelwise
analysis of the data using GLM, in order to perform linear regression on the
data based on a clinical variable. When we then analyse the data with
Randomise (using n = 5000, c = 3), the unthresholded t-stat image shows
regions of reduced FA that correlate with reduced gestational age (t > 3, p
< 0.05). Looking at the multiple comparison-corrected cluster p-value image,
however, this difference does not appear significant in any brain regions (t
> 3). Do you think we are being too harsh in our multiple comparison
corrections? Would it be possible for you to have a look at our data? I’ve
uploaded the t-stat images and the design matrix and design contrast files
(upload ID 680318).
Also, are we correct in thinking that we can correct for age at scan by
including this as a second EV and demeaning the data?
Thank you very much for your help.
With best wishes,
Mustafa
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Mustafa Anjari
Robert Steiner MRI Unit
Imaging Sciences Department
Imperial College London
Hammersmith Hospital
Du Cane Road
London W12 0HS
UK
Tel: +44 20 838 32336
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