Hi,
I consulted my statistician and figured out the answer to my last question about pca, but have a few new ones for you that he could not answer.
1. After running 3dpca I open AFNI and go to the "func" and "thresh" buttons to select the map I want to see. The first sub-brik is labeled "var=100.62%" Is this the score of the first component? If so why/how can it be greater than 100% ? I ran the program several times on different subjects, and they all had similar results (first sub-brik greater than 100%). What am I not understanding?
2. What is the significance of the "functional" value of each voxel? Could you explain how those numbers are generated. Also, what is a reasonable value at which to "threshold" them? (or do I just play with it till I get a reasonable looking map?)
Thanks!
Sara
