Hello! I'm designing an experiment with 5 factors. Factor X1 is Ingredient Type, a two-level categorical variable (Ingredient A or Ingredient B). But we also want to investigate the concentration of both ingredients. Ingredient A has a range of 5% to 20%, while Ingredient B has a range of 1% to 10%. I can't include this as three independent factors.
I see two reasonable options:
- Run two sequential experiments. First run a screening experiment with X1 as a two-level categorical variable, to find which Ingredient Type gives a better response. Second, run an optimization experiment to investigate concentration of the better ingredient.
- Run one experiment, but make X1 a four-level categorical variable: A-high, A-low, B-high, B-low.
Two questions for the community: Which of these two options is better? Is there a better option that I'm not thinking of?
Many thanks to the community!