Experimental Design - Summary for Variables (Factors)
Factor values (e.g., Low value, High value, Center value) vary with each type of design. If a particular factor value is only available for specific designs, that is indicated in the descriptions below.
After you enter the lower and upper values for the three components (0 <= xA <= 800; 200 <= xB <= 800; 0 <= xC <= 800, Total = 800) into the Specifications for Mixture Variables spreadsheet, and then click the OK button, the following message will be displayed:
The selected specifications (highs, lows, and mixture total) are inconsistent and have to be adjusted to produce a standard design; do you want to adjust the factor highs?
If you click the Yes button, then the Specifications for Mixture Variables spreadsheet will be displayed again with the adjusted values that permit Statistica to construct the standard design in a sub-triangle (or sub-simplex). Specifically, when there are lower constraints for one or more of the components, the program will adjust the High Value for the other components, so that:
x'high,i = Total-Li
Here, x'high,i stands for the adjusted High Value for the i'th component, Total stands for the mixture total, and Li stands for the sum of the lower constraint (limit) for all components excluding component i.
See also, Design of Experiment with Two-Level Factors, Design of a Screening (Plackett-Burman) Experiment, Design of an Experiment with Three-Level Factors, Design of an Experiment with Two- and Three-Level Factors, Design of a Mixture Experiment, and Design of a Central Composite (Response Surface) Experiment.