Hi Yolanda,
you computed the percent change, now I think you want to see if it is different from zero. You don't need groups. qdec should be able to test difference from zero. If you use mri_glmfit there is a flag -osgm (one sample group mean).
Cheers, Martin ----- Original Message ----- From: Yolanda Vives To: Martin Reuter Cc: freesurfer Sent: Wednesday, July 04, 2012 7:27 AM Subject: Re: [Freesurfer] Extraction Longitudinal Stats
Hi Martin,
When I convert my long qdec table to a cross sectional table to analyze for exemple percent change maps, I have some difficulties to identify my independent factor in this case, because I don't have two groups like in the longitudinal study (On-Off). Could you please help me to build this cross table from my long table?
Exemple of my longitudinal table:
fsid fsid-base group preJMS_007 JMS_007 ON postJMS_007 JMS_007 OFF preRME_063 RME_063 ON postRME_063 RME_063 OFF ...
Thank you very much, yolanda
2012/7/4 Yolanda Vives yvives@pic.es
Hi Martin,
Thank you for your answer. I am also interested in testing your new scripts, if it is possible.
Regards, Yolanda
2012/7/3 Martin Reuter mreuter@nmr.mgh.harvard.edu
Hi Yolanda,
take a look at the longitudinal tutorial: http://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/LongitudinalTutorial
There is a section that hints at the post-processing as far as we have implemented it. Based on a longitudinal qdec table you can run long_mris_slopes to create rate or percent change maps for each subject and then run qdec on these for the cross sectional comparison.
Also I can make available a newer version of that script as lots of small things have changed since last year, let me know.
Best, Martin
On Tue, 2012-07-03 at 15:58 +0200, Yolanda Vives wrote: > Hi Martin, > > I would like to compare also a Control vs. an Experimental group > (pre-post), but instead of using ROIs, I am interested in a > whole-brain paired t-test analysis between the two groups. Which data > should I take? Would it be possible to process ?.long.base with qcache > and take the "rh.thickness.fwhm20.fsaverage.mgh" files? Or maybe could > I use QDEC with ?.long.base after qcache? > > Thank you, > Yolanda > > 2012/4/12 Martin Reuter mreuter@nmr.mgh.harvard.edu > Yes, just extract the stats on each time point as done in a > cross > sectional analysis (but instead on the ?.long.base > directories) do a > paired t (or a t on the difference) to see if there is > increase or > decrease. > > If you look at one of the reported ROI's (e.g. caudate volume, > or > pre-central thickness) you can directly get the values from > the stats > files. If you have your own ROI's you need to use segstats to > get the > stats for them. > > Cheers, Martin > > On Wed, 2012-04-11 at 19:19 +0200, Dídac Vidal wrote: > > Hi everybody, > > I have a question about FS longitudinal post-processing. > Currently I > > obtained some corrected results comparing a Control vs. an > > Experimental group (pre-post). > > What i would like to know is if there's a thinning in the > control > > group or a increase in the thickness of the experimental > group. > > I tought in create a label and extract the individual values > of both > > timepoints and then do a t test in order to see if the mean > differs to > > 0. > > How I can do that?; There is an easier way to do it? > > Thanks in advance > > > > -- > > Dídac Vidal Piñeiro > > > > Dept. Psychiatry and Clinical Psychobiology > > Faculty of Medicine > > University of barcelona > > > > > > > _______________________________________________ > > 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 > > > 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. > > > >