Experimental Design - Trace Plots for Mixture Experiments

Options for creating trace plots are available from both the Quick tab and the Prediction & profiling tab of the Analysis of a Mixture Experiment dialog box.

Suppose you look at the contour plot of the response surface for three components. Then, determine a reference blend for two of the components; for example, hold the values for A and B at 1/3 each. Keeping the relative proportions of A and B constant (i.e., equal proportions in this case), you can then draw a line representing the different values for C. You can plot the estimated response (values for the dependent variable) for different values of C, while holding the relative amounts of A and B constant. If the reference blend for A and B is 1:1, then the line or response trace amounts to the axis for factor C, that is, the line from the C vertex point connecting with the opposite side of the triangle at a right angle. However, trace plots for other reference blends can also be produced. Typically, the trace plot contains the traces for all components, given the current reference blend.