Profiler - Quick Tab

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

Set factors at

Use the options in the Set factors at group box to specify the current levels of the predictor variables for the prediction profile compound graph and for surface and contour plots.

Mean values

Select the Mean values option button to set the current level of each predictor variable to the mean of the respective variable.

User specified

Select the User-specified option button to set the current level of each predictor variable to values that you specify. Click the adjacent    button to display the Select factor values dialog box, in which you specify the current level for each predictor variable.

At optimum value

Select the At optimum value option button to set the current level of each predictor variable to the value determined by optimizing the response desirability. Desirability is optimized with the Use general function optimization method or the Optimum desirability at exact grid points method, as specified by selecting the respective option button on the Profiler dialog box - Options tab.

Note: the options in the Set factors at group box can be used sequentially to specify start values for the simplex search for optimal response desirability in the Use general function optimization method. To specify the means of the predictor variables as start values, select the Means values option button (see above) to set the current levels of the predictor variables at their respective means, and then select the At optimum value option button (see above). To specify values other than the factor means as start values, select the User-specified option button (see above), enter the desired start values as the current levels of the respective predictor variables in the Select factor values dialog, and then select the At optimum value option.

If the Use general function optimization method is selected on the Profiler dialog box - Options tab, the current levels of the predictor variables will be used as the start values for the simplex search for the optimal response desirability. The solution for the optimal response desirability using the Optimum desirability at exact grid points method can even be used as start values for the Use general function optimization method for optimizing response desirability. See the Profiler dialog box - Options tab topic for a discussion of this technique, which can be especially useful for specifying values that may approximate the solution, improve the speed of finding a solution for large analyses, and prevent failure to converge at a solution.

Block

Enter a value in the Block box to specify the current level of the blocking factor, if a blocking factor is included in the analysis. Any valid block setting can be entered in this box, and will be used as the current level of the block factor for the prediction profile compound graph and for surface and contour plots. Note that if a search for the optimum response desirability has been conducted by selecting the At optimum value option button (see above), the optimal value of the block factor will be displayed in the Block box. Note that the Block box is not available if there is no blocking factor in the analysis.

Factor grid

Use the Factor grid options to specify the experimental range and the grid points for each of the predictor variables in the analysis. Use the box adjacent to the Factor grid button to specify the factor for which you want to specify grid points. Click the Factor grid button to display the Specifications for Factor Grid dialog box, in which you specify the minimum value, the maximum value, and the number of intervals in the grid for the factor. These specifications determine the grid points for the factor by setting the lowest grid point to the minimum value, the next lowest grid point to the minimum value plus the difference of the minimum value from the maximum value divided by the number of intervals, and so on up to the highest grid point.

Grid points serve two functions in the Profiler. They determine the plot points for the factors on the prediction profile compound graph and the surface and contour plots. They also determine the levels of the factors for which predicted values for the dependent variables are computed when the Set factors At optimum value option button is selected (see above) and the Optimum desirability at exact grid points method is specified on the Profiler dialog box - Options tab. Large numbers of grid points should be avoided when these options are used to avoid unexpectedly long grid searches (see the Profiler dialog box - Options tab topic for details). Changing the grid points for the factors only affects the graphical output if the Set factors At optimum value option is not selected, or the Optimum desirability at exact grid points method has not been specified.

Note: for mixture designs, the specified factor minimum and maximum values must be within the observed range of values for the respective factors. This constraint does not apply for other types of designs.

Desirability function. When the Show desirability function check box is selected (see below) all the options will be available in the Desirability function group box.

Show desirability function

Select the Show desirability function check box in order to enable the options in the Desirability function group box. The Show desirability function check box is always selected when the Set factors At optimum value option (see above) is selected. If the Set factors At optimum value option has been selected and the Show desirability function check box is cleared, Statistica will clear the At optimum value option button and select the User-specified option button.

Variable

Use the Variable box to select a dependent variable for which to specify desirability function settings.

Note: Desirability Function Settings. When the Show desirability function check box is set, you can enter desirability function specifications for the dependent variable displayed in the Variable box. These specifications determine the desirability function values (from 0.0 for undesirable to 1.0 for very desirable) corresponding to predicted values on the dependent variable. These specifications are entered in the edit fields for the Desirability function settings, each of which is described below.

Value - Low, Medium, and High Values

Statistica allows for up to three "inflection points" in the desirability function for predicted values for each dependent variable. For example, suppose that some intermediate predicted value on a dependent variable is highly desirable, and that lower and higher predicted values on the variable become progressively less desirable as they depart further from the "target" intermediate value. This type of desirability function would have three inflection points: the low value for the dependent variable, below which the response is undesirable, the high value for the dependent variable, above which the response is undesirable, and the medium value for the dependent variable, at which the response becomes increasingly desirable as it approaches the target value. The default specifications for the low value, medium value, and high value settings use a simple "higher is better" type of desirability function with only two inflection points. The low value is set to the observed minimum value for the dependent variable, the high value is set to the observed maximum value for the dependent variable, and the medium value is set to the mid-point between these two extremes. You can specify any other type of desirability function with up to three inflection points by entering the inflection points for the variable in the low value, medium value, and high value boxes. The only restriction is that adjacent inflection points must be in ascending order or equal in value.

Desirability - Low, Medium, and High Values

Desirability values (from 0.0 for undesirable to 1.0 for very desirable) can be specified for the corresponding inflection points of the desirability function for each of the dependent variables. For the example "target" type of desirability function described above, you would want to specify desirability values of 0.0 for responses with values below the low inflection point or above the high inflection point, and a desirability value of 1.0 for the targeted intermediate value. You would therefore specify values of 0.0, 1.0, and 0.0 for desirability in the low value, medium value, and high value boxes. The default specifications for the level of desirability at the three inflection points are based on a simple "higher is better" type of desirability function. Desirability is set to 0.0 at the low value, 0.5 at the medium value, and 1.0 at the high value. You can specify any other valid desirability values (from 0.0 to 1.0) by entering the appropriate value in the respective boxes.

s and t (curvature) parameters

The desirability of responses need not decrease (or increase) linearly between inflection points in the desirability function. Perhaps there is a "critical region" close to a desired, intermediate response on a dependent variable beyond which the desirability of the response at first drops off very quickly, but drops off less quickly as the departure from the "targeted" value becomes greater. To model this type of desirability function requires "curvature" parameters to take into account the nonlinearity in the "falloff" of desirability between inflection points. In the s parameter and t parameter boxes, you can specify a value for the exponent of the desirability function (from 0.0 up to 50, inclusive) representing the curvature in the desirability function between the low and medium inflection points of the function, and between the medium and high inflection points of the function, respectively. Assuming that an intermediate response is most desirable, values greater than 1.0 for the s parameter and t parameter represent initial quicker "falloff" in desirability but subsequent slower "falloff" in desirability as the departure from the "targeted" value becomes greater. Values less than 1.0 for the s parameter and t parameter represent initial slower "falloff" in desirability but subsequent quicker "falloff" in desirability as the departure from the "targeted" value becomes greater. The default specifications for the s parameter and t parameter are values of 1.0, representing linear "falloff" in desirability between the medium and low inflection points as well as between the medium and high inflection points. Further descriptions of the s parameter and t parameter and their effects in the desirability function can be found in the discussions of "two-sided" desirability functions in Derringer and Suich (1980) and in Box and Draper (1987).

Apply to all vars

Click the Apply to all vars button to apply the desirability settings you specify for one dependent variable to all the dependent variables in the analysis. This option is particularly useful if the same dependent variable is measured on, say, successive days. For example, you could specify the desirability of radioactivity readings of waste materials on the first day after the materials are discharged from a factory, then apply the same desirability settings for the radioactivity readings on subsequent days. If many days of readings are taken, the Apply desirability specifications to all variables option can save considerable data entry.

Reset specs

Click the Reset specs button to reset any changed desirability function settings for a dependent variable back to the default desirability function specifications for the variable (for details on default specifications, see Desirability function settings, above).

for all vars

Click the for all vars button to reset all desirability function settings for all dependent variables back to the default desirability function specifications (for details on default specifications, see Desirability function settings, above).