afni.nimh.nih.gov

Hello,

Sorry for not getting to this.

Yes, polort regression is very similar to high-pass filtering, though it is a *little* different, since the regressors do not span the same space.

The reason going above polort 2 is not so useful is because a slow cubic is pretty well modeled by a sine function (plus a quadratic). The higher degree polorts are not so useful when a bunch of sinusoids are already in the model.

- rick