Thank you very much for your answer. Are 10 000 iterations also used when I am running a Monte Carlo simulation in qdec?
Thanks, Marie 2012/6/9 Douglas N Greve <gr...@nmr.mgh.harvard.edu> > they are two different correction schemes. If they gave the same answer, > then it would not make sense to have both. the monte carlo tries to > compute the probability of a cluster of the given size under the null > hypothesis. FDR controls for the number of false positives relative to > the total number of positives under the assumption that if any 5% of > your positives are false, then you would not change your conclusion. > > For monte carlo, we generally use 10000 iterations. If you are using the > whole hemisphere, then you can used the cached tables. See the > "command-line" tutorial. > > doug > > On 06/08/2012 08:03 AM, Marie Schneider wrote: > > Dear FreeSurfer experts, > > > > I have some questions about corrections for multiple comparisons in > > FreeSurfer. I have two samples, one consisting of two groups and one > > consisting of three groups. > > > > I do the comparison with the sample of two groups in qdec. Correcting > > for multiple comparisons, I get a significant result using FDR, but no > > significant result using Monte Carlo simulation. How can that be? > > > > I analyze the sample with the three groups by mri_glmfit. In your > > tutorial, I only found how to correct for multiple comparisons with > > the Monte Carlo simulation using the command line, but not how to > > correct with FDR using the command line. Is there a possibility to do > > this? If not, how many iterations are usual to use within the Monte > > Carlo simulation? > > > > Any help is appreciated. > > > > Thank you very much, > > > > Marie > > > > > > _______________________________________________ > > Freesurfer mailing list > > Freesurfer@nmr.mgh.harvard.edu > > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > -- > 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: www.nmr.mgh.harvard.edu/facility/filedrop/index.html > > _______________________________________________ > 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. > >
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