DOE - Split Plot Designs: Does one ever include center points?
Greetings: I'm new to split plot designs, understand the basic structure and application. Does one ever include center points in such a design to detect curvature? I've searched and searched, but haven't been able to find an answer. I suspect the answer is "No", but if anyone out there can refer a document or has an answer, I'd love to know the reason. Cheers, Bruce