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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Vincent Costa
June 21, 2006 06:48PM
I am attempting to analyze an fMRI experiment in which a cognitive always occurs at the offset of a stimulus that is invariant in its duration. Ideally, I would like to deconvolve the BOLD signal in response to the stimulus and then the cognitive task, but I am concerned about collinearity.

When I evaluate the experiemental design using the -nodata option in 3dDeconvolve the program generates the inverse matrix, but the error is sizable and outputs the following message:

++ Matrix inverse average error = 0.0234375 ** WARNING!!! **

So, what is an acceptable average error (<.05 ?). If I were to proceed with this format of deconvolution what trouble might I expect to run into?

Vinny
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Subject Author Posted

When to heed warnings about collinearity

Vincent Costa June 21, 2006 06:48PM

Re: When to heed warnings about collinearity

Zhark, Emperor June 22, 2006 08:47AM

Re: When to heed warnings about collinearity

Vincent Costa June 22, 2006 10:06AM

Re: When to heed warnings about collinearity

Colm Connolly October 08, 2007 07:25AM

Re: When to heed warnings about collinearity

bobcox October 08, 2007 09:45PM