Design of a Mixture Experiment - Display Design Tab

Select the Display design tab of the Design of a Mixture Experiment dialog to access options to review the design summary and to change the factor names or values.

Summary: Display design

Click the Summary: Display design button to display a spreadsheet that specifies the settings for each experimental run. The way in which the design is displayed is affected by the settings of the options on the Display design tab. To save the design, select the spreadsheet and use the Save or Save As options via the File menu. Note that to use this spreadsheet in further analyses, you must specify it as an input spreadsheet. For more information, see the Input Spreadsheet Overview.

Note: Partial replications. If you want to replicate selected points from the design (e.g., so that you can later obtain an estimate of pure error; see the Introductory Overview), first add rows to the design (use option Insert - Add Cases), and then copy and paste the respective runs into those new rows.

Change factor names, values, etc

Click the Change factor names, values, etc. button to display the Specifications for Mixture Variables spreadsheet containing (1) the current factor (component) names, (2) minimum and maximum values, and (3) the sum total for the mixture. Enter the desired text and numeric values, and then click the OK button; the values that you enter are used in the spreadsheet displaying the design (option Summary: Display design, see above). See Summary for Variables (Factors) for more details. See also, General User Entry Spreadsheet.

Denote factors

Use the options in the Denote factors group box to determine how the factors are labeled in the spreadsheet. See the note on denoting factors for more details.

By numbers

Select the By numbers option button to denote the factors by numbers; that is, to label consecutive factors as F1, F2, ..., Fn.

By letters

Select the By letters option button to denote the factors by letters; that is, to label consecutive factors as A, B, C, and so on.

By names

Select the By names option button to denote the factors by their names, as specified via the button Change factor names, values, etc., on the respective results dialog.

Order of runs

The choice of options in the Order of runs group box affects the order of runs displayed in the spreadsheet. For standard experiments, it is common practice to randomize the runs in order to avoid any systematic biases due to fluctuations in the production process across runs.

Standard order

Select the Standard order option button to display the design in standard order.

Random

Select the Random option button to randomize the order of runs.

Seed

The positive integer value in the Seed box is used to seed the random number generator. Note that the random number generator is reseeded every time you enter the Design of a Mixture Experiment dialog. Thus, when you generate the same designs more than once, the default random seed in the Seed box will be different every time. If you want to generate the identical order in consecutive analyses, enter into this box the same number as that shown in the initial analysis. In practice, since randomization is supposed to accomplish unbiased assignment of runs to experimental conditions, you usually do not want to change this value.

Show (in Spreadsheet). The selection of options in the Show (in Spreadsheet) group box determines the way in which the factors are displayed in the spreadsheet.

Standard values (0, 1, etc.). Select the Standard values option button to change the display to show the respective standard design, where the factor lows and highs are equal to 0 and 1, respectively, and the mixture total is equal to 1.0.

Factor values (highs, lows)

By default, the Factor values option button is selected, and, if not changed, the levels of the factors are denoted by the respective factor lows and highs.