Profiler - Options Tab

Select the Options tab of the Profiler dialog box to access the options described here.

Intervals

Use the options in the Intervals group box to determine which intervals are shown along with the predicted values on the prediction profile compound graph.

None

Select the None option button if you prefer to show no intervals on the graph.

Confidence intervals

The Confidence intervals option button is selected as the default setting. Accept this setting to show confidence intervals on the graph.

Prediction intervals

Select the Prediction intervals option button to show prediction intervals on the graph.

Search options (for optimum desirability)

Use the options in the Search options (for optimum desirability) group box to specify the search for the optimum response desirability.

Use general function optimization

The Use general function optimization option (the simplex method of function optimization) is usually faster, but the default method is Optimum desirability at exact grid points (see below), except when the number of predicted values that must be computed to perform the exhaustive grid search exceeds 200,000, in which case Use general function optimization becomes the default.

Optimum desirability at exact grid points

Select the Optimum desirability at exact grid points option button to perform exhaustive searches for the optimum desirability at exact grid points. The number of predicted values that must be computed to perform an exhaustive grid search is the product of the number of intervals plus one for each factor, the number of block levels, and the number of dependent variables. For example, a three factor, two block analysis with four intervals per factor and four dependent variables would require computation of 1000 predicted values (5 x 5 x 5 x 2 x 4 values) to perform an exhaustive search for Optimum desirability at exact grid points.

To avoid long grid searches in analyses involving many factors, blocks, and dependent variables, the following strategy is suggested. Set the number of intervals for each factor to a small number, perhaps 2 (see Specifications for Factor Grid for details on specifying these values). Perform an initial exhaustive search by selecting the Optimum desirability at exact grid points option button, and then select the Use general function optimization option button for a final search. This has the effect of providing values that may approximate the solution as start values for the general function optimization, improving the speed of finding a solution, and preventing failure to converge.

To summarize, with fine grids and large numbers of independent and dependent variables, the Optimum desirability at exact grid points option can take a long time to run, but it will always find the optimal settings of the factors. The Use general function optimization option is generally faster, but for data sets with several local minima in overall desirability, or when the maximum desirability is close to the edge of the experimental region, this option can sometimes fail to converge or fail to find the maximum desirability.

Options for profile plots

Use the Options for profile plots group box to specify whether to Show spreadsheets with plotted values, Label cont/pred limits for pred. values, and Show text vals for factor settings.

Show spreadsheets with plotted values

Select the Show spreadsheets with plotted values check box to specify that spreadsheets with profile plot data be produced along with the compound graph of the prediction profiles for each of the dependent variables. One spreadsheet will show the predicted values of the dependent variables at each grid point for each predictor variable (and each level of the block factor, if there is a block factor in the analysis). A second spreadsheet will show the current levels of each predictor variable and the predicted values of the dependent variables at the current levels of the predictor variables. Confidence intervals or prediction intervals for the predicted values are also shown if the Confidence intervals option or the Prediction intervals option, respectively, is selected (see above). If the Show desirability functions check box is selected on the Profiler dialog box - Quick tab, a third spreadsheet will show the specified Desirability function settings. In short, these spreadsheets provide a full listing of all values plotted in the compound graph of the prediction profiles.

Label conf/pred limits for pred. values.

Select the Label conf/pred limits for pred. values check box to specify that confidence/prediction limits are labeled on the compound graph of the prediction profiles for each of the dependent variables.

Show text vals for factor settings

Select the Show text vals for factor settings check box to display the text labels for the dependent variables on the compound graph of the prediction profiles.

Fit options for desirability surface/contours

Several methods are available for fitting surfaces/contours to the desirability values for surface/contour plots. The Spline method is the default, but you can select the Quadratic surface, Least squares, or Negative exponential method by selecting the respective option button.

Note: Mixture designs. For mixture designs, there is a different set of fit options. The Quadratic method is the default, but you can select the Linear, Special cubic, or Full cubic method by selecting the respective option button.

Show the grid points

Select the Show grid points check box to specify grid points to be shown on contour and surface plots for each of the dependent variables.