AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

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Sara
December 23, 2003 10:19AM
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
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another pca question

Sara December 23, 2003 10:19AM