Analyzing the mean and standard deviation response surfaces

Analyzing the mean and standard deviation response surfaces 

One analysis approach, appropriate if there are only a couple of design variables, is to construct contour plots of the mean response and the standard deviation of the response over the range of the variables. This will enable the researcher to see the constraints and trade-offs that may need to be made to achieve required values for the mean and variability of the response. 

The choice of whether to make the mean the primary or the secondary response will depend on the objectives of the experiment. For example, if the objective is to have the mean on target with minimum variation then the dual response approach would suggest minimizing the variance (or 

The application of the standard nonlinear programming techniques of constrained optimization on analyzing the mean and variance response surfaces has been investigated by Del Castillo and Montgomery [34]. These techniques are appropriate since both the primary and secondary responses are usually quadratic functions. 

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