Modifying and Using Worksheet Data
overview      

When you create a design using one of the Create Design procedures, Minitab creates a design object that stores the appropriate design information in the worksheet. Minitab needs this stored information to analyze and plot data properly.

The following columns contain your design:

·    StdOrder

·    RunOrder

·    CenterPt (two-level factorial and Plackett-Burman designs)

·    PtType (split-plot, general full factorial, response surface, and mixture design)

·    Blocks

·    factor or component columns

If you want to analyze your design with the Analyze Design procedures, you must follow certain rules when modifying worksheet data. If you make changes that corrupt your design, you may still be able to analyze it with the Analyze Design procedures after you use one of the Define Custom Design procedures.

·    You cannot delete or move the columns that contain the design.

·    You can enter, edit, and analyze data in all the other columns of the worksheet, that is, all columns beyond the last design column. You can place the response and covariate data here, or any other data you want to enter into the worksheet.

·    You can delete runs from your design. If you delete runs, you may not be able to fit all terms in your model. In that case, Minitab will automatically remove any terms that cannot be fit and do the analysis using the remaining terms.

·    You can add runs to your design. For example, you may want to add center points or a replicate of a particular run of interest. Make sure the levels are appropriate for each factor or component and that you enter appropriate values in StdOrder, RunOrder, CenterPt, PtType, and Blocks. These columns and the factor or component columns must all be the same length. You can use any numbers that seem reasonable for StdOrder and RunOrder. Minitab uses these two columns to order data in the worksheet.

·    You can change the level of a factor for a botched run in the Data window.

·    You can change factor level settings using Modify Design. However, you cannot change a factor type from numeric to text or text to numeric.

·    You can change the name of factors and components using Modify Design.

·    You can use any procedures to analyze the data in your design, not just the procedures in the DOE menu.

·    You can add factors to your design by entering them in the worksheet. Then, use one of the Define Custom Design procedures