Hi Anderson,
Thanks Anderson,I see.
For the 1st question,did I need demean behavior data when I used -D option?
For the 2nd question,what I think below are appropriate?
1,Output of randomise is an inference based on non-paramatric method, and result from FEAT is an inference based on paramatric method.
2,For VBM and TBSS(for gray matter and white matter respectively),can I use the same GLM setup which is used for randomise previously to perform paramatric inference by FEAT at the end(not by randomise)? That is to say, I want to use FEAT not randomise to perform paramatric inference.
Thanks again, Anderson.
All the best.
Rujing Zha
 
2014-02-07

charujing123

发件人:Mark Jenkinson <[log in to unmask]>
发送时间:2014-02-07 17:45
主题:Re: [FSL] question about "randomise -D option" and "GLM design in Two-Group Difference"
收件人:"FSL"<[log in to unmask]>
抄送:
 
Hi,

The -D option in recent versions of FSL removes the mean from both the data and the design matrix EVs.

Permutations and t-tests are not mutually exclusive.  You are still using t-tests (or F-tests if you combine t-tests) in randomise, but the method by which it performs inference (calculating probabilities) uses a permutation-based non-parameteric method, as opposed to tools like FEAT where parametric methods are used.  This is totally separate from the fact that you are performing a t-test.

All the best,
Mark


On 7 Feb 2014, at 03:12, charujing123 <[log in to unmask]> wrote:

Hi Anderson and other FSL experts,
I have a two questions about FSL statistics.
1,As we know, there is a -D option in randomise,which is "demeaning data temporally before model fitting". What I wonder is -D option demean what data, either only MR data or both for MR data and behavior data?
2,http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/GLM#Two-Group_Difference_.28Two-Sample_Unpaired_T-Test.29 In method of this website, I can do two-sample unpaired t-test. In "randomsie details", I see word "permutations". So I didnot know whether it is a unpaired t-test or a permutaion test.There is same question in "Two-Group Difference Adjusted for Covariate". If they are all t-test, I want to know the functions of permutations and how to do permutation test.
Thanks Anderson and others.
All the best.
Rujing Zha
 
2014-02-07

charujing123