我笑着哭Notice that Design-Expert correctly changed the inequality to greater than (>). Now we turn our attention back to factor A (temperature) and its Constraint Point. It must be at least 180 when B (time) is at its vertex (low) level.
Constraint point set for A
Notice that Design-Expert previously changed the inequality to greater than (>), which is correct.
Press OK to see that Design-Expert calculated the same multilinear constraint equation that we derived mathematically.
Resulting multilinear constraint equation
Press OK to accept this inequality constraint. Then press Continue.
Design-Expert 8 User’s Guide D-Optimal RSM Tutorial 5
Building an optimal design
Leave the Search option default of “Best” and Optimality on the “IV” criterion. Take a moment now to read the helpful information provided on screen, which provide some pros and cons to these defaults. Note that we recommend the IV optimal for response surface designs like this. In the next tutorial, which shows how to handle a categorical factor for RSM, you will use an alternative criterion called “D-optimal.” about the “Optimal Model Selection Screen.”
Screen tips provide detail on all the choices for optimal design specifications Feel free to click the link that explains how Design-Expert uses the Best search from coordinate and point exchange. Exit out (X) of the tips for “Optimal Model Selection Screen.” Press the Edit Model button to upgrade the default model of quadratic to Cubic. (Recall that the experimenter suspects the response might be ‘wavy’ – a surface that may not get fit adequately with only the default quadratic model.)
Cubic model specified
6 D-Optimal RSM Tutorial Design-Expert 8 User’s Guide
