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If you do multiple testings, e.g. on different components, yes. hth, andreas Am 09.04.2013 um 23:15 schrieb "Franklin, Crystal G" <[log in to unmask]>: > Thank you Andreas. Makes sense. > > One last question. When we are running the t-test, should we correct for multiple comparisons? > > Thanks, > Crystal > > From: "Andreas J. Bartsch" <[log in to unmask]> > Reply-To: FSL - FMRIB's Software Library <[log in to unmask]> > Date: Tuesday, April 9, 2013 3:58 PM > To: "[log in to unmask]" <[log in to unmask]> > Subject: Re: [FSL] FDG PET with Melodic > > Hi, > > you won't get a spatial map of the difference in your case. You get a spatial map of the average effect and, by using the time point entries (=subjects in your case) you can test for differences of the average effect across groups (i.e. ordered subjects) outside FSL (using R, matlab - whatever you fancy). Does that make sense? > Cheers, > Andreas >> "Franklin, Crystal G" <[log in to unmask]> hat am 9. April 2013 um 22:44 geschrieben: >> >> Steve, >> >> We have taken the melodic_mix data and performed an unpaired t-test on the components we are interested in. Now we are having trouble interpreting the results. What does it mean if we see a significant group difference in a component? We are also noticing for some components we are getting a negative and positive group mean, how do we interpret this? >> >> Thank you, >> Crystal >> >> From: Stephen Smith < [log in to unmask]> >> Reply-To: FSL - FMRIB's Software Library < [log in to unmask]> >> Date: Tuesday, April 9, 2013 10:39 AM >> To: " [log in to unmask]" < [log in to unmask]> >> Subject: Re: [FSL] FDG PET with Melodic >> >> You already have this - the spatial ICA maps. >> >> >> On 9 Apr 2013, at 16:35, "Franklin, Crystal G" < [log in to unmask]> wrote: >> >>> Will we be able to get a map from this? >>> >>> Crystal >>> >>> From: Stephen Smith < [log in to unmask]> >>> Reply-To: FSL - FMRIB's Software Library < [log in to unmask]> >>> Date: Tuesday, April 9, 2013 10:24 AM >>> To: " [log in to unmask]" < [log in to unmask]> >>> Subject: Re: [FSL] FDG PET with Melodic >>> >>> Hi >>> In this case the ICA "time series" are the subject weights - so (e.g.) read melodic_mix into Matlab, identify the column number that matches the spatial map component number that you "like" - and then do a statistical test between different timepoints (subjects) in that column of weights. >>> Steve. >>> >>> >>> >>> On 9 Apr 2013, at 16:13, "Franklin, Crystal G" < [log in to unmask]> wrote: >>> >>>> Thank you for your quick response. >>>> >>>> So I have concatenated all my single subject images into a 4D NIFTI image and ran them through Melodic using single-session. Now I have my components, but I am stuck on how to get my group differences. Any suggestions? >>>> >>>> Thank you, >>>> Crystal >>>> >>>> From: Stephen Smith < [log in to unmask]> >>>> Reply-To: FSL - FMRIB's Software Library < [log in to unmask]> >>>> Date: Tuesday, April 9, 2013 9:21 AM >>>> To: " [log in to unmask]" < [log in to unmask]> >>>> Subject: Re: [FSL] FDG PET with Melodic >>>> >>>> Hi - yes this should be possible. If you have "time series" data for each subject then you should use group-ICA and dual-regression; if you only have a single summary image per subject then you should concatenate all images into a 4D NIFTI image and run "single-session" (default) melodic. >>>> >>>> Steve. >>>> >>>> >>>> On 9 Apr 2013, at 14:22, "Franklin, Crystal G" < [log in to unmask]> wrote: >>>> >>>>> Dear FSL, >>>>> >>>>> I have a FDG PET study that contains 79 subjects that are either FH+ or FH-. The data has already been preprocessed and registered into standard space. I am now wanting to do an ICA analysis to get the components and then do group comparisons with these components. Is this possible and if so, how do I go about setting this analysis up. >>>>> >>>>> Thank you, >>>>> Crystal >>>> >>>> >>>> --------------------------------------------------------------------------- >>>> 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 >>>> --------------------------------------------------------------------------- >>>> >>> >>> >>> --------------------------------------------------------------------------- >>> 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 >>> --------------------------------------------------------------------------- >>> >> >> >> --------------------------------------------------------------------------- >> 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 >> --------------------------------------------------------------------------- >> > >