[Freesurfer] optseq2 polynomial order

Hi there,

I noticed that when I include additional polynomials as nuisance variables, the efficiency of the design decreases. When should we include polynomials to account for scanner drift, and how do we decide the maximum order of the polynomials? Does it depend only on the length of the run? My runs are 8 min each, am I justified in having a quadratic polynomial?

Thank you,

Leo Fernandino

------------------- Leonardo Fernandino, Ph.D. Post-Doctoral Scholar Human Neuroscience Laboratory Department of Neurology The University of Chicago 5841 S. Maryland Ave. MC-2030 Chicago, IL 60637 Phone: (773)-834-7847 http://www.fmri.uchicago.edu/

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