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Hi, This SnPM_ST file is a collection of voxel values and locations for high t-scores (the tip of t-image iceberg) from all the permutations, to be used in a cluster size test later on. From my experience, using variance smoothing (or pseudo-t) seems to accelerate the growth of SnPM_ST, especially when there aren't large activation areas. A possible remedy for this problem is to change the variable called "SnPMdefs.STprop" in snpm_defaults.m. The default is 0.10, but try a smaller number (eg., 0.05, 0.025, and so on) until SnPM_ST becomes a manageable size. Alternatively, you can try SnPM with a regular t-image instead of a psudo-t image. Good luck! -Satoru Satoru Hayasaka ============================================== Post-Doctoral Fellow, MR Unit, UCSF / VA Medical Center Email: shayasak_at_itsa_dot_ucsf_dot_edu Phone:(415) 221-4810 x4237 Homepage: http://www.sph.umich.edu/~hayasaka ============================================================== At 09:37 AM 6/20/2005 +0200, Roland Marcus Rutschmann wrote: >Hi, > >after having "played" successfully with some 2nd level fMRI statistics and >snpm I tried another larger dataset. This consists of 18 subjects and >whole-brain functional images. > >After running out of disc space severall times I think my problem is not the >nr of subjects but whole brain images. So the combination of 10 subjects, >whole brain images, pseudo t-statistics (and thus the volumetric eval.), and >collecting sub-threshold statistics with only about 200 permutations leads to >a file size of SnPM_ST.mat which cannot be loaded anymore. (size about 1GB -> >load SnPM_ST.mat fails). > >Is that just me or is this reproducable. What are the rules of thumb of data >sets that still can be handled? > >The whole calc works btw for another data set with 10 subjects and about >half-brain images or with the whole-brain images if I not choose the >volumetr. calculation. And it's of course only a problem for cluster >statistics. > >This happened on a debian sarge system with 2GB RAM and 2GB swap space under >both matlab 6.5 and 7. > >Thanks for any help, > >Roland > >-- >Dr. Roland Marcus Rutschmann <[log in to unmask]> >Institute for Experimental Psychology, University of Regensburg >Universitätsstraße 31, 93053 Regensburg, Germany >Tel: +49 941 943 2533, Fax: +49 941 943 3233 >http://www.psychologie.uni-regensburg.de/Rutschmann