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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
| January 21, 2014 11:22AM | |
I fitted some data (20s stimulus) using the SPMG3(20) model and got results like the one shown below (fit in blue):
Are there no constraints on the combinations of the basis functions? I am just wondering how this peculiar shape with the 3 peaks can happen, it seems like an overfitting problem.
My goal is anyway to show that this model performs poorly for this particular data compared to afnis nonlinear regression.
But I think it is known that unconstrained basis sets can produce quite nonsensical shapes, which a reviewer might criticize.
How does the official spm software handle this? maybe there are some hard constraints how much of the temporal/spatial derivative can be added.
Edited 1 time(s). Last edit at 01/21/2014 11:25AM by paranoidandroid.
Are there no constraints on the combinations of the basis functions? I am just wondering how this peculiar shape with the 3 peaks can happen, it seems like an overfitting problem.
My goal is anyway to show that this model performs poorly for this particular data compared to afnis nonlinear regression.
But I think it is known that unconstrained basis sets can produce quite nonsensical shapes, which a reviewer might criticize.
How does the official spm software handle this? maybe there are some hard constraints how much of the temporal/spatial derivative can be added.
Edited 1 time(s). Last edit at 01/21/2014 11:25AM by paranoidandroid.
| Subject | Author | Posted |
|---|---|---|
|
paranoidandroid | January 21, 2014 11:22AM |
|
gang | January 22, 2014 11:03AM |
|
Daniel Glen | January 22, 2014 12:12PM |
