Storing the Design
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If you want to analyze a design, you must store it in the worksheet. By default, Minitab stores the design. If you want to see the properties of various designs before selecting the design you want to store, uncheck Store design in worksheet in the Options subdialog box.

Every time you create a design, Minitab reserves and names the following columns:

·    C1 (StdOrder) stores the standard order.

·    C2 (RunOrder) stores run order.

·    C3 (PtType) stores a numerical representation of the type of design point.

·    C4 (Blocks) stores the blocking variable. When a design is not blocked, Minitab sets all column values to one.

·    C5,... ,Cnumber of components + 4 stores the components. Minitab stores each component in your design in a separate column.

·    In addition, depending on your design and storage options, Minitab may store the following:

-    each process variable in a separate column (named X1,... ,Xn)

-    an amount variable (named Amount)

-    the design parameters (named Totals, Lower, Upper, Linear)

If you named the components or process variables, these names display in the worksheet. After you create the design, you can change the component names directly in the Data window or with Modify Design.

If you did not change the total for the mixture from the default value of one, Minitab uses proportions to store your data. If you did change the total for the mixture, Minitab uses amounts - what you actually measure - to express your data. After you create the design, you can specify one of three scales (see Specifying the units for components) to represent the data: amounts, proportions, or pseudocomponents. To change which of the three scales is displayed in the worksheet, use Display Design.

Caution

When you create a design using Create Mixture Design, Minitab stores the appropriate design information in the worksheet. Minitab needs this stored information to analyze the data properly. If you want to use Analyze Mixture Design, you must follow certain rules when modifying the worksheet data. See Modifying and Using Worksheet Data.

If you make changes that corrupt your design, you may still be able to analyze it with Analyze Mixture Design after you use Define Custom Mixture Design.