Hi - see recent emails on the list about symmetry testing - and there  
will be a new FLS patch in the next couple of days that includes a new  
script for doing symmetry testing.
Cheers.


On 19 May 2009, at 17:20, Long Chuan wrote:

> Hi, Matthew
> Thank you very much for your information.
> I have a few further questions regarding this and would really  
> appreciate if you would shed some light on.
> Since my data were derived from TBSS and the major purposes are to  
> investigate 1) hemisphere effect, 2) handedness effect and 3)  
> interaction of the two, I am wondering if it is correct for me to  
> use the following statistics to check what I want to see:
>
> Data preparations:
>
> 1)    Original FA maps (36 subjects) and their flipped FA maps were  
> fed into TBSS processing pipelines. A symmetrical FA template was  
> used for the FA images to register on.
> 2)    Then, the right hemisphere of the derived 4D FA (totally 72  
> volumes) skeleton was masked out and the statistics were carried on  
> the left half, the first 36 volumes represented the FA images on the  
> right hemisphere (from the flipped images) and the next 36 volumes  
> represent original FA images.
>
> Statistics:
> 1) Handedness measures were continuous ranging from [-1, 1].  
> However, correlation results did not show significance between  
> handedness index and asymmetry quotient of FA on a voxel basis ( AQ  
> = (FA_L – FA_R)/(FA_L + FA_R). therefore, I divided the subjects  
> into two groups (based on their handedness and conducted group  
> analysis).
> 2) One sample paired t-test on FA difference map (Left hemisphere  
> subtracts right hemisphere) was used to check hemisphere effect;
> 3) Two sample unpaired t-test with age as nuisance covariate on FA  
> map to check handedness effect;
> 4) Two sample unpaired t-test with age as nuisance covariate on FA  
> difference map to check hemisphere-by-handedness effect;
>
> Are these tests correctly set up to let me see what I want to check?  
> If not, is there a more efficient way to set up the design?
>
> Many thanks in advance
> Longchuan
>
>
> From: Matthew Webster <[log in to unmask]>
> To: [log in to unmask]
> Sent: Tuesday, May 19, 2009 11:29:49 AM
> Subject: Re: [FSL] 2-by-2 ANOVA using randomise
>
> Hi,
>     Randomise can handle the within-subject factor by using the -e  
> option. It currently is unable to deal with between-subject factors  
> for this kind of analysis, although we are intending to enable this  
> feature in future versions.
>
> Many Regards
>
> Matthew
>
> > From: Long Chuan <[log in to unmask]>
> > Date: 14 May 2009 21:56:35 BST
> > To: [log in to unmask]
> > Subject: [FSL] 2-by-2 ANOVA using randomise
> > Reply-To: FSL - FMRIB's Software Library <[log in to unmask]>
> >
> > Hi, FSL experts
> >
> > I think I have posted similar questions before but this question  
> is still confusing me.
> > I have run TBSS registration on a group of subject. I measured the  
> handedness of the subjects. What I am interested in seeing are 1)  
> hemispheric effect, 2) handedness effect and 3) the interaction of  
> the two. By searching the old archives, it seems to me that  
> randomise in this version cannot take care of 2-by-2 repeated ANOVA   
> (between subject factor of handedness and within-subject factor of  
> hemisphere, also age is used as covariate).
> >
> > So my question is:
> > 1) Is there any way that I can model this 2-by-2 ANOVA design in  
> randomise and get the results in a single run? If not, what is the  
> most proper way to carry this analysis in randomise?
> >
> > Any suggestions or advice is greatly appreciated
> >
> > Longchuan
>
>


---------------------------------------------------------------------------
Stephen M. Smith, Professor of Biomedical Engineering
Associate Director,  Oxford University FMRIB Centre

FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
+44 (0) 1865 222726  (fax 222717)
[log in to unmask]    http://www.fmrib.ox.ac.uk/~steve
---------------------------------------------------------------------------