Mike, I have run such tests in the past (which showed about 2-3% variability in hippo volume due to randomness) and Doug has done similar tests, but admittedly running a large scale analysis and showing the results on a wiki page would be useful. Something like running our Buckner40 and/or ADNI60 data set, making 20 copies of each subject and including the -randomness flag, and plotting the mean/std of the volume and surface rois.
Nick > Nick might have, not sure. Are you volunteering Mike :) > > On Wed, 20 Jun 2012, Michael Harms wrote: > >> >> I'm curious: For comparison to the results in that paper, has anyone >> quantified the variability that results when one runs the same FS >> version repeatedly on the same subject, but with a different random seed >> each time? That is, how much of the difference is related to math >> libraries vs. intrinsic variability that arises from the components of >> FS that use a random seed? >> >> cheers, >> -MH >> >> On Wed, 2012-06-20 at 10:43 -0400, Bruce Fischl wrote: >>> Hi Peter >>> >>> thanks for the info. Feel free to post this on one of the *many* blogs >>> howling for our blood :) I think that the effects in the paper reflect >>> default floating point settings in gcc on 32-bit vs. 64-bit, although >>> we >>> haven't really investigated as it doesn't seem like a wise use of >>> limited >>> resources (since no one would ever do a study that way in any case). >>> >>> Bruce >>> >>> >>> On Wed, 20 Jun 2012, Peter J. Molfese wrote: >>> >>>> We run things on an Xgrid cluster that is now a mixture of Macs >>>> running Snow >>>> Leopard (10.6.8) and Lion (10.7.x). We found the results given from >>>> asegstats2table and aparcstats2table are identical after running 100 >>>> subjects on both Mac OS X 10.7.4 and 10.6.8 with Freesurfer 5.1. I >>>> also ran >>>> a few subjects on the cluster and on individual computers (not on the >>>> cluster so to speak) and the results are identical. >>>> >>>> Best, >>>> Peter >>>> >>>> >>>> Hi, >>>> >>>> The paper entitled >>>> >>>> ?The Effects of FreeSurfer Version, Workstation Type, >>>> and Macintosh Operating System Version on Anatomical >>>> Volume and Cortical Thickness Measurements?, >>>> PLoSONE, Vol 7(6), e38234 (2012) >>>> >>>> may be of interest to all of you. It can be found at: >>>> >>>> http://dx.plos.org/10.1371/journal.pone.0038234 >>>> >>>> Cheers, >>>> Ed >>>> >>>> >>>> >>>> >>> _______________________________________________ Freesurfer mailing list >>> Freesurfer@nmr.mgh.harvard.edu >>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer 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. >> >> >> > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer
