Thanks for your quick post. As followup or clarification, a fairly
standard and simple test for curvature in this situation is to compare the
average of the center points to the average of the corner points. If this
difference is big enough then you probably have curvature and this warrants
further study to identify which factor(s). I can do this test manually in
JMP but thought that a fairly standard test like this would be displayable
somewhere in the dialogue. If not, so be it.