This is actually something that you cannot currently do in QDEC. Try doing a search for "paired" on our wiki for instructions on how to do this type of analysis. doug
Joana Braga Pereira wrote:
Dear Freesurfers,
I'm doing a longitudinal analysis of cortical thickness using the newest version of Freesurfer and there is something i would like to ask you all.
I have two time points and only one group of patients.
I've finished the pre-processing and am now searching for differences between the two time points using Qdec.
Since i only have one group my cross.qdec.table.dat file looks pretty much like this:
fsid years template_M_b01 0.665 template_M_b02 0.665 template_b03 0.71 template_b04 0.79 template_b05 0.915 template_b07 0.665 template_b09 0.625 template_b10 0.625 template_b11 0.71 template_b13 1.04 template_b14 0.71 template_b15 0.665 template_b16 0.835 template_b17 0.665 template_b18 0.625 template_M_b19 0.71 template_M_b20 0.625 template_b21 0.71 template_b22 0.585
I selected the long.thickness.rate in Qdec interface and years as continuous covariate since it is the only variable that i have in my cross.qdec.table.dat (no groups or other covariates of interest).
My question is: Is this the analysis i should be doing given that i want to know the differences between time point 1 - time point 2?
Many thanks,
Joana
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