I don't know, esp since it is an approximation to begin with. An alternative is to take the offsets from your multi-time-point subjects and the single maps from your subjects with one time point and run that through the one-sample-group-mean (--osgm in mri_glmfit). If you go this route, then you should subtract the mean age of the one time-point subjects from the age of the multi-time point subjects before the 1st stage of analysis.
doug On 03/02/2015 07:25 PM, Janosch Linkersdörfer wrote: > Hi Doug, > > thank you very much for your answer! > > Am 02.03.2015 um 11:30 schrieb Douglas N Greve <gr...@nmr.mgh.harvard.edu>: > >> You would do the long analysis using a random effects analysis. > OK, so basically do 2-stage modeling > (https://surfer.nmr.mgh.harvard.edu/fswiki/LongitudinalTwoStageModel), right? > >> For each subject you can get a slope (this won't work if the subject only >> has 1 time point), then concatenate the slopes into a file and run >> mri_glmfit, then follow the procedures from the archive email you reference. > One quarter of my subjects only has one measurement time point. Can I still > use this method (which would only consider the 3/4 of the subjects) to > correct clusters found in the whole group? Or would it only be valid for > correcting clusters from an LME model for the reduced group? > > Thanks, > > Janosch > >> doug >> >> On 02/24/2015 08:35 PM, Janosch Linkersdörfer wrote: >>> Hi Doug and others, >>> >>> I would like apply (Monte Carlo simulation) cluster correction (as opposed >>> to the implemented vertex-wise FDR correction) on the results from a >>> longitudinal study I analyzed using the LME toolbox. The design is >>> unbalanced (different number of time points, from 1 to 4, per subject). >>> >>> In this thread >>> (http://www.mail-archive.com/freesurfer%40nmr.mgh.harvard.edu/msg35367.html) >>> you, Doug, suggested, if I understand correctly: >>> >>> - concatenating the images using `mris_preproc --paired-diff` >>> - smooth with the same kernel size as used in the lme analysis >>> - running `mri_glmfit` on them with an fsgd file that uses the same >>> covariates and the same contrast (excluding the interaction term with time) >>> as used in the lme analysis >>> - overwriting sig.mgh with the one from the lme analysis >>> - running `mri_glmfit-sim --cache` >>> >>> How would I extend this to my case where I don't have pairwise images, but >>> 1 image for some participants, for others up to 4? >>> >>> Thanks a lot, >>> >>> Janosch >>> >>> >>> >>> >> -- >> Douglas N. Greve, Ph.D. >> MGH-NMR Center >> gr...@nmr.mgh.harvard.edu >> Phone Number: 617-724-2358 >> Fax: 617-726-7422 >> >> Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting >> FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 >> www.nmr.mgh.harvard.edu/facility/filedrop/index.html >> Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ >> >> >> >> The information in this e-mail is intended only for the person to whom it is >> addressed. If you believe this e-mail was sent to you in error and the e-mail >> contains patient information, please contact the Partners Compliance >> HelpLine at >> http://www.partners.org/complianceline . If the e-mail was sent to you in >> error >> but does not contain patient information, please contact the sender and >> properly >> dispose of the e-mail. >> > > -- Douglas N. Greve, Ph.D. MGH-NMR Center gr...@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
