Dear SPM user
The order of regressors within the designmatrix of spm (spm5) does matter
because all regressors get orthogonalized to the first one (spm_orth.m). I'm
interested in the severity of this effect and tested this having two simple
boxcar function with high colinearity of r=.7 within the design matrix and
run two separate analysis with switched regressor order. Surprisingly the
two regressor had the identical activation independet of their order in the
designmatrix. I', pretty sure not done any mistakes. How is this to explain?
Thanks for any comments
RL
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