JMP DOE Setting a range for my factors

Question

Hello,

I am new to JMP and am trying to create a simple DOE where I am trying to maximize growth in a reactor by using different agitation rates, thus my agitation is my factor and my growth is my response. My issue is whenever I try to make a custom DOE I can not set a range for my factors, all there is are values and whenever I make my DOE it just uses the two values I entered. I want to set an upper and lower limit for my factor and not just use two values. I am setting my factor as continuous. Any help would be appreciated.

Mark_Bailey · Answer

@pauldeen explained how to get more than two levels for a continuous factor. You pick the terms to represent the effects and JMP picks the levels. An alternate way is to add a Discrete Numeric factor. Now you pick the levels and JMP picks the terms.

pauldeen · Answer

In Custom DOE In the factor definition you only define the range of experimentation. By adding polynomial terms in the model definition you can force extra points (for a quadratic you will get a mid point) and every order higher will give you one more point optimally spaced between your range limits.

Mark_Bailey · Answer

Another issue is that the design depends on the model you want to estimate. The default model will be an intercept and a single term for agitation rate. That is to say, JMP assumes that you expect a linear change in the growth when you change the agitation. The best design in that case is to observe only at the low and the high values. These observations provide the highest leverage in the regression analysis. For example, if you added a center point to this design, it would have zero leverage in estimating the slope.