DOE with different components and their concentrations together with a component constraint

Marjoleine

When we want to do a DoE with 4 different components A, B, C and D and also a few others and we want to vary each component A,B,C,D in a concentration from eg. 20-70 phr but at the same time when A is in the mixture, B,C and D should be absent and vice versa.  If I make them categorical I have only 1 at the same time but then I can’t choose the concentration and if I make it continuous I can’t choose between them. Has someone a better option?

Dan_Obermiller

Use a categorical variable with 4 levels. The levels will be A, B, C, and D and will tell you which of the four components to use in that run. Then one mixture component that takes in the range 0.2 to 0.7 (JMP typically uses proportions instead of percentages) that tells you the amount of that component. Then you can add the "few other components " as additional mixture components.