Optimal Design Result: Response Surface - Confounding Tab

Select the Confounding tab of the Optimal Design Result: Response Surface dialog box to access options to review the correlation matrix for the design matrix, and thus to determine the confounding of main effects and interactions.

Summary: Efficiency measures

Click this button to produce a spreadsheet containing the summary of efficiency measures. For a description of these efficiency measures, see Efficiency Measures for D- and A-Optimal Designs. Note that the D- and A- efficiency measures are only reported if the current model is a response surface (and not a mixture) model, and when the factors are recoded to the ±1 range (see the D- and A-Optimal Designs - Options tab). For a discussion of the different optimality criteria, refer to the Introductory Overview.

Correlation matrix

Click the Correlation matrix button to display a correlation matrix of the columns of the current design matrix. If the current design is a mixture design, then these coefficients are computed without the intercept, that is, as the standardized sums of the raw cross-products.

Inverse correlation matrix

Click the Inverse correlation matrix button to display (1) the inverse of the correlation matrix, and (2) the standardized inverse of that correlation matrix. This matrix can be interpreted as the correlation matrix of effects; that is, it is the standardized variance/covariance matrix of the parameter estimates for the current model. The greater the absolute value of a correlation between effects in this matrix, the more redundant are the respective effects.

2D Scatterplot of points

Click the 2D Scatterplot of points button to display a scatterplot of the final design points for two factors. If there are more than two factors in the current design,after clicking the 2D Scatterplot of points button, the Select factors for 2D scatterplot dialog box will be displayed. In this dialog box, select the two factors for the 3D scatterplot.

3D Scatterplot of points

Click the 3D Scatterplot of points button to produce a 3D scatterplot of the design points. If there are more than three factors in the current design,after clicking the 3D Scatterplot of points button, the Select factors for 3D Scatterplot dialog box will be displayed. In this dialog box, select the three factors for the 3D scatterplot.