Contour Plots Definition Form

A contour plot shows the response surface for two factors with all of the other factors held constant at levels you specify. Use this form to select which factor will be used on the horizontal and which factor will be used on the vertical axis.

When you have selected your factors, you can zero in on an area of interest by limiting the range to be plotted. You may limit the range for either or both factors.

Note that this is particularly useful with mixture designs where you are going to graph mixture factors on the axes and you have remaining factors that are process factors. For example, if you have four mixture factors, all of which may range from 0 to 100 in the design, you can put two of the mixture factors on the axes. That means that you have one more factor that was used in the regression and a fourth mixture component factor that was deliberately left out of the regression. You must account for all four when you set the ranges.

Let’s take this example a little further. We four mixture factors, we’ll call them A, B, C, and D. We want to put A and B on the axes of the contour plots. Factor C is in the model and we are going to set C at -.5 (25%). Factor D is not in the model, but we must also account for it as the remaining factor. Let’s say that we want to also set D at 25%. (You can’t do that directly because D is not in the model, but you still must account for D.) The way to do that is to set the range correctly here. Factor A and Factor B can only range from 0 to 50 at most because you need the rest of the mixture for 25% C and 25% D.

Such a graph will show points where both A and B are at values cannot occur when C=25% and D = 25%. Namely, when A=20% and B=40% cannot occur in the mix since then the total exceeds 100% which is absurd.

Slices Tab

Levels Tab

Special Tab

Files Tab

Cancel will return you to the Main Menu.

Continue creates the plot arrays.