Back to PLS HelpPosted on 07/21/14 12:19:20
Number of posts: 2
Hello, I was wondering if anyone could help me with a small problem I am having. I am preprocessing my data with afni and I am successfully able to run PLS when I create the sessiondata from aligned, tailarached, and blurred images; however if I try to run PLS with sessiondata that has an additional detrend step (via using AFNI's 3dDetrend command-which removes the effects of motion and linear quadratic and cubic drifts from the time series) I get this error "ERROR: no common coords among datamats!". 3dDetrend does not change the coordinate system so I am stumped. I also noticed that within the sessiondata.mat the st_coords does not have anything in it whereas if I cretae the sessiondata without the detrend step it does. Is it the actual creation of the sessiondata.mat that is the problem or is there something that 3dDetrend does to the data that PLS is opposed to? If so, why am I able to create the sessiondata with no errors? Thanks in advance for any insight.
Amanda
Replies:
Posted on 07/21/14 12:44:21
Number of posts: 394
Hello, I was wondering if anyone could help me with a small problem I am having. I am preprocessing my data with afni and I am successfully able to run PLS when I create the sessiondata from aligned, tailarached, and blurred images; however if I try to run PLS with sessiondata that has an additional detrend step (via using AFNI's 3dDetrend command-which removes the effects of motion and linear quadratic and cubic drifts from the time series) I get this error "ERROR: no common coords among datamats!". 3dDetrend does not change the coordinate system so I am stumped. I also noticed that within the sessiondata.mat the st_coords does not have anything in it whereas if I cretae the sessiondata without the detrend step it does. Is it the actual creation of the sessiondata.mat that is the problem or is there something that 3dDetrend does to the data that PLS is opposed to? If so, why am I able to create the sessiondata with no errors? Thanks in advance for any insight.
Amanda
I suspect it has to do with the changes in the voxel values after detrending to have positive and negative values. Its technically not necessary to detrend the data for PLS, but if you want to use these data, you may wish to create a binary mask from your data and use that to create the sessiondata rather than using a calculated threshold.
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