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 FSL Repeated Measures ANOVA?
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Jeff_Browndyke
Junior Member

35 Posts

Posted - Oct 14 2013 :  2:45:35 PM  Show Profile  Visit Jeff_Browndyke's Homepage  Reply with Quote
I've been working with FSL basic TBSS scripts with relative success, but being a FSL novice I've been using the processing recipe here: http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/tbss/UserGuide

This guide, however, only provides help on constructing design.mat and design.con files for basic 2-sample t-tests. I'm trying to figure out how to construct a repeated measures x 2 sample ANOVA (i.e., group x time) for 12 patients and 12 controls to examine differences in FA between baseline and 6wk post-op and their interaction. Does anyone know how to code this sort of model in FSL and the required contrasts? I looked at the code in the design.mat and design.con files for the 2-sample and that code seems pretty simple, but I'm not certain what to do about a repeated measures ANOVA where within- and between-variance needs to be computed.

BTW - I'm processing all four timepoints together to obtain an overall study specific mean FA skeleton and have named the files alphabetically to indicate the groups by timepoints (e.g., Controls Tp1 = A0...n; Patients Tp1 = B0...n; Controls Tp2 = C0...n; Patients Tp2 = D0...n).

Thanks for any help, tips, pointers, etc.

Jeff

petty
BIAC Staff

USA
453 Posts

Posted - Oct 14 2013 :  3:20:11 PM  Show Profile  Reply with Quote
Hey Jeff,

You can should be able to open the Glm design tool ( "Glm" ) and set-up an 2x2 anova identical to the one described here:
http://fsl.fmrib.ox.ac.uk/fsl/fsl4.0/feat5/detail.html#ANOVA2factors2levels

You just have to make sure you are concatenating your subjects in the same order as you have them defined in the Glm
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Jeff_Browndyke
Junior Member

35 Posts

Posted - Oct 14 2013 :  3:29:38 PM  Show Profile  Visit Jeff_Browndyke's Homepage  Reply with Quote
Thanks, Chris! I'm assuming that I cannot use "randomize?" The TBSS script line I've been using for the 2-sample procedure with TFCE correction and 500 permutations is:

randomise -i all_FA_skeletonised -o tbss_FA -m mean_FA_skeleton_mask -d design.mat -t design.con -n 500 --T2 -V

Regards,
Jeff
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petty
BIAC Staff

USA
453 Posts

Posted - Oct 14 2013 :  3:35:15 PM  Show Profile  Reply with Quote
no, you keep using randomise .. Set-up your glm with Glm, but now you'll need design.mat, design.con and design.fts

So add this flag to your randomise line:
	-f <design.fts>	f contrasts file

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Jeff_Browndyke
Junior Member

35 Posts

Posted - Oct 14 2013 :  3:37:48 PM  Show Profile  Visit Jeff_Browndyke's Homepage  Reply with Quote
Cool. Thanks again!
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