My question is related to the use of Response Surface Methodology (RSM) for optimization of independent variables having compositional variation during substrate addition. Say, for example, i have identified 4 factors that are significantly affecting a given response (or process). These are for example pH, Temperature, substrate loading and time. Now, pH, temp, and time is governed by high and low levels, the values of which can be provided at the time of design of experiment. However, the substrate part is not only influenced quantitatively by lower and higher concentrations (that is amount of substrate added) but can also be affected by composition of substrate. The substrate which we are talking is a mixture of 3 different feed stocks.
Now, the question is that which design is best suited so that the qualitative and quantitative both variations can be singly incorporated for optimization of any response.
Hoping a positive reply.
Kshitiz