#Screening DoE

[#1]

i have excipient A of 4 different grades, how Can I include all those 4 different grades in a Denitive Screening DOE?

[#2]

The short answer is you can't. Definitive screening designs are not suited for 4 level factors. Your best bet, lacking any additional insight into the other factors, your experimental goals and objectives, your responses, etc. is to investigate optimal DOE tactics...these are supported in JMP in the Custom Design platform.

[#3]

My initial reaction is why are you testing at 4 levels if you are doing screening?  The objective of screening designs for the most part is to examine a large number of factors in an efficient number of treatments.  This is done using the principles of scarcity, hierarchy and heredity of effects.  A 4-level factor allows for estimation of effects of hierarchy beyond what screening designs are intended to do.  Can you pick the extremes of the 4 levels (which grades do you think will be the most different?) and test that factor at 2-levels?