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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 ---------------------------------------------------------------------------