Re: [Freesurfer] Longitudinal prediction

2014-10-31 Thread Alex Hanganu
I see. Thank you Doug ! Now I used the command lines from the qdec output in the terminal and I constructed the next contrasts using them as a starting point. Now the results seem more reliable and I can perform the Monte-Carlo with 5000 iterations.  I'll verify them once again with LME. Alex.

Re: [Freesurfer] Longitudinal prediction

2014-10-31 Thread Douglas N Greve
--osgm is for one-sample group mean which is the simplest design possible. It is probably not appropriate for your design. If you have different inputs and different labels then you will get different results On 10/30/2014 03:08 PM, Alex Hanganu wrote: > Hi Martin, > > could you please confirm

Re: [Freesurfer] Longitudinal prediction

2014-10-30 Thread Alex Hanganu
right ! I totally forgot about this ! Thank you Martin ! Sincerely,Alex  On Thursday, October 30, 2014 3:33 PM, Martin Reuter wrote: Hi Alex, the QDEC output (text in the terminal) should have the command line that was used to call the mri_glmfit command. Best, Martin

Re: [Freesurfer] Longitudinal prediction

2014-10-30 Thread Martin Reuter
Hi Alex, the QDEC output (text in the terminal) should have the command line that was used to call the mri_glmfit command. Best, Martin On 10/30/2014 03:08 PM, Alex Hanganu wrote: Hi Martin, could you please confirm whether the glm analysis was correctly performed ? the command line is:

Re: [Freesurfer] Longitudinal prediction

2014-10-30 Thread Alex Hanganu
Hi Martin, could you please confirm whether the glm analysis was correctly performed ? the command line is:mri_glmfit --glmdir DIR --y lh.thickness-pc1.stack.fwhm15.mgh --label lh.fsaverage.cortex.label --fsgd FSGD_FILE --C Contrast-010..0.mtx --surf fsaverage lh  I get results, but I when I do t

Re: [Freesurfer] Longitudinal prediction

2014-10-23 Thread Martin Reuter
Hi Alex, you are not looking at a "one sample group mean" (osgd) so don't pass that flag. Your design is probably something like 1 A other_co_vars_to_regress_out (these are column vectors). so contrast in that case would be [ 0 1 0... ] That should create all outputs. All of this is really cr

Re: [Freesurfer] Longitudinal prediction

2014-10-23 Thread Alex Hanganu
Hi Martin, thanks for confirming. I duplicated the parameter and got good results in qdec. I also tried to repeat the analysis with mri_glmfit but I can't manage to come to an end.In order to analyse the correlation between pc1 and parameter 'A', it seems that I have to construct an fsgd file, th

Re: [Freesurfer] Longitudinal prediction

2014-10-21 Thread Martin Reuter
Hi Alex, you have to duplicate the parameter (it is basically fixed across time). If you put 0 for tp2, it will average the two values, which is not what you want. Otherwise I think it is the correct approach. Best, Martin On 10/21/2014 04:31 PM, Alex Hanganu wrote: Dear Martin, thank you

Re: [Freesurfer] Longitudinal prediction

2014-10-21 Thread Alex Hanganu
Dear Martin, thank you very much for your answer ! and thanks for all the details !- yes, we have exactly 2 time points in all subjects and the parameter is a single number. In qdec - it seems that qdec table has to include the parameter 'A' both at time 1 and at time 2 in order for "long_qdec_ta

Re: [Freesurfer] Longitudinal prediction

2014-10-21 Thread Martin Reuter
Hi Alex, the parameter is a single number that happens to be measured at time 1 right, eg baseline age? Lets call that parameter 'A' for the discussion below. Also you have exactly 2 time points in all subjects? There is two alternatives: 1. Simple approach (2-stage-model): You compute the

[Freesurfer] Longitudinal prediction

2014-10-20 Thread Alexandru Hanganu
Dear FreeSurfer Experts, How could the longitudinal analysis be performed in order to show whether a parameter at time 1 is predictive of changes in cortical thickness over time ? and can thecorresponding regions be shown in FreeSurfer ? In a statistical analysis, as we see it, we must perfo