Thank you for the quick reply!

When I run that command to test for numeric values, I get a 1.

I am actually using a somewhat odd dataset that actually represents the mean value of cortical parcels over time. I wouldn't expect that to have a bearing on this particular issue though. The data file is a nifti file that has the following dimensions:




In writing this, I just realized the answer might be that the analysis I ran in SPM prior to the PPPI may have altered the original data somehow even though it is already completely preprocessed. My unfamiliarity with SPM may have led me to leave on a filtering step or the like that altered the input data. Is that a possibility?

I have attached a zip file with the data file, my mask file, and the SPM.mat file from the GLM analysis. I'm trying to get data from the first voxel, 1,1,1 (1-indexed).

Thanks for your help!

Andrew