I set up a test matrix with 3 centerpoints. When I run the model script in JMP the lack of fit analysis only uses the first two centerpoints for the calculations. Is there a way to set the number of used centerpoints to 3?
JMP will automatically use all available data for an analysis. How do you know that only two center points are being used? If you are basing it off of the degrees of freedom in the lack of fit test, remember that degrees of freedom for the pure error term will be number of replicates minus 1. If only the center points are replicated, that would be 2 degrees of freedom.