Use Define Custom Design to create a design from data you already have in the worksheet. Use a general full factorial design when the factors can have any number of levels and you want to treat all factors as categorical.
Usually, you define a custom design for one of the following reasons:
- You created a design in Minitab and modified the worksheet so that Minitab could no longer analyze the design. For example, Minitab cannot analyze the design if you move or delete the column that contains the standard order of the design.
- You typed the design information directly into the worksheet.
- You imported the design from a non-Minitab file.
- You created the design using Minitab Session commands.
- You created the design with a version of Minitab older than version 13.
For example, an engineer has a general full factorial design in a Microsoft Excel spreadsheet. The design has 256 runs. The engineer wants to reduce the size of the design. The engineer opens the spreadsheet in Minitab. Then, the engineer defines the design as a custom general full factorial design. Last, the engineer uses Minitab to select an optimal design.
Where to find this analysis
When to use an alternate analysis
- If the design includes a hard-to-change factor, define a 2-level split-plot design.
- If all of the factors have only 2 levels, not including center point runs, then you can define a custom 2-level factorial design.