Fitting a response surface model with four factors (one factor is a nuisance factor)
I've designed a DoE to study the influence of factors on a filtration process. First, I designed a fractional factorial DoE to investigate 4 factors at two levels (low and high) and also includes two center points. In the evaluation, I find that one of the four factors has no influence on the responses and is not considered in further DoE designs. The design is then augmented to include star point...