Response Surface Designs Overview
overview    see also 

Response surface methods are used to examine the relationship between a response variable and a set of experimental variables or factors. These methods are often employed after you have identified a "vital few" controllable factors and you want to find the factor settings that optimize the response. Designs of this type are usually chosen when you suspect curvature in the response surface.

Response surface methods may be employed to

·    find factor settings (operating conditions) that produce the "best" response

·    find factor settings that satisfy operating or process specifications

·    identify new operating conditions that produce demonstrated improvement in product quality over the quality achieved by current conditions

·    model a relationship between the response and continuous and categorical factors

Many response surface applications are sequential in nature in that they require more than one stage of experimentation and analysis. The steps shown below are typical of a response surface experiment. Depending on your experiment, you may carry out some of the steps in a different order, perform a given step more than once, or eliminate a step.

1    Choose a response surface design for the experiment. Before you begin using Minitab, you must determine what the influencing factors are, that is, what the process conditions are that influence the values of the response variable. See Choosing a Design.

2    Use Create Response Surface Design to generate a central composite or Box-Behnken design.

Use Define Custom Response Surface Design to create a design from data you already have in the worksheet. Custom designs allows you to specify which columns are your factors and other design characteristics. You can then easily fit a model to the design and generate plots.

3    Use Modify Design to rename the factors, change the factor levels, replicate the design, and randomize the design.

4    Use Display Design to change the order of the runs and the units in which Minitab expresses the factors in the worksheet.

5    Perform the experiment and collect the response data. Then, enter the data in your Minitab worksheet. See Collecting and Entering Data.

6    Use Analyze Response Surface Design to fit a model to the experimental data.

7    Use Contour and Surface Plots for response surface designs to visualize response surface patterns. You can display contour and surface plots.

8    If you are trying to optimize responses, use Response Optimizer or Overlaid Contour Plot to obtain a numerical and graphical analysis.