Hi Lanbo,

the first command computes the slope of within-subject linear fits (the rate, so the unit is mm/time). You use —generic time which means that the time is 1 2 3 … It is better to put the real time, e.g. in years for a longitudinal study.

the second command is a one-sample-group-mean (OSGM) analysis to test whether the slopes are significantly different from zero. The sig.table.dat shows the significances (log 10 , so 1 is p=0.1, 2 is p=0.01 etc, with a sign showing the direction).

Now if you look at regular aging and if you have enough subjects and wait for a year or two all regions in the brain should show significant atrophy. So the OSGM is not very interesting usually. For a real study you usually need two groups (diseased vs control, or drug vs no-drug)

Best, Martin

On 27. Oct 2017, at 20:13, lanbo Wang drrambow@gmail.com wrote:

Dear freesurfer group,

Hi! I used long_stats_slopes and code to process my longitudinal data: long_stats_slopes --qdec sub_qdec_long.dat --stats lh.aparc.stats --meas thickness --sd $SUBJECTS_DIR --do-rate --generic-time --stack-rate thickness.lh.aparc-rate.stack.txt mri_glmfit --osgm --glmdir thickness.lh.aparc-rate --table thickness.lh.aparc-rate.stack.txt I got results sig.table.dat in folder of 'thickness.lh.aparc-rate'. I want to ask what's meaning of this results. Is it the significant results or just directly result?

All best, Lanbo Wang <sig.table.dat>_______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer