Hi Doug
I hope it's okay that I double check I'm doing the correction over 2 hemispheres correctly and ask a question regarding correction for multiple comparisons. I will briefly describe what I have done:
I have 2 groups of subjects - Drug addicts (n= 17) and controls (n=20).
1. I ran a surface thickness study:
· For the 'mri_glmfit' command, I used DOSS and specified a contrast of +1 -1 0 (Controls > MA)
· I ran a pre-cached simulation with the following command: mri_glmfit-sim --glmdir lh.group_age.glmdir --cache 4 pos
· This simulation should only have corrected for the left hemisphere as I understand it. My cluster summary text file showed me that a cluster survived in the insula. I interpreted this as 'controls had higher grey matter thickness in this cluster located in the insula than drug addicts'. However, this was only corrected over the left hemisphere (when I ran the same simulation in the right hemisphere, nothing survived multiple comparison correction).
· I now wanted to correct the lh results for 2 hemispheres. From the help menu of 'mri_glmfit-sim', I understood you can do this in 2 ways, are both of these correct and give the same result?
a. mri_glmfit-sim --glmdir lh.group_age.glmdir --cache 4 pos --2 spaces --no-sim csdbase
b. mri_glmfit-sim --glmdir lh.group_age.glmdir --cache 4 pos --cwpvalthresh 0.025
Ø No clusters survived the Bonferroni correction over both hemispheres. So I assume I can no longer report this result?
2. I ran a subcortical volume study:
· I used SPSS to perform the statistical analysis on each of 14 subcortical structures (left and right). Is there a good way to correct for multiple comparisons, apart from Bonferroni, which would be very conservative?
Many thanks for your advice.
Kind regards Reem
Reem Jan BPharm (Hons), RegPharmNZ
PhD Student / Pharmacist School of Pharmacy, Faculty of Medical & Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand. Ph: +64 9 373 7599 ext 81138. DDI: +64 9 923 1138 F: +64 9 367 7192
From: freesurfer-bounces@nmr.mgh.harvard.edu [mailto:freesurfer-bounces@nmr.mgh.harvard.edu] On Behalf Of Douglas Greve Sent: Friday, 20 July 2012 11:52 a.m. To: freesurfer@nmr.mgh.harvard.edu Subject: Re: [Freesurfer] slice-by-slice predictors
Sorry, not possible.
On 7/19/12 6:56 PM, Caspar M. Schwiedrzik wrote: Hi! Is it possible to have slice-by-slice predictors in Freesurfer, and if so, how? Thanks, Caspar
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