Numerical Optimization

Choose the desired goal for each factor and response from the menu. The possible goals are: maximize, minimize, target, within range, none (for responses only) and set to an exact value (factors only.)

A minimum and a maximum level must be provided for each parameter included. A weight can be assigned to each goal to adjust the shape of its particular desirability function. The “importance” of each goal can be changed in relation to the other goals. The default is for all goals to be equally important at a setting of 3 pluses (+++). If you want one goal to be most important, you could change it to 5 pluses (+++++).

The goals are combined into an overall desirability function. The program seeks to maximize this function. The goal seeking begins at a random starting point and proceeds up the steepest slope to a maximum. There may be two or more maximums because of curvature in the response surfaces and their combination into the desirability function. By starting from several points in the design space chances improve for finding the “best” local maximum. The default is 30 starting points. You can change this via the Options button.

Contour, 3D surface, and perturbation plots of the desirability function at each optimum can be used to explore the function in the factor space. Also, any individual response may be graphed to show the optimum point.