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To create a Taguchi orthogonal array design, follow the steps outlined next. For more general information on building designs, see Building a New Design.
Choose Insert > DOE > Add Standard Design to add a standard design folio to the current project.
Select Design Type in the folio's navigation panel, and then select Taguchi OA Factorial in the input panel.
If you wish to rename the folio, click the heading at the very top of the navigation panel (the Experiment1 heading in the above example) and edit the Name field in the input panel.
Define the response(s) for the design. To edit the first response, click Response1 in the navigation panel and then edit its properties in the input panel. To add a response, choose Experiment > Responses > Add Response.
Define the factors. With the currently selected design type, you must have at least two factors, and all factors must have two levels. Factors are defined in a similar way to defining responses. (See Adding, Removing and Editing Factors.)
Click Additional Settings in the navigation panel and specify the settings described next.
General Settings
Replicates allows you to specify the number of test units you want to observe at each combination. In other words, the number of replicates is the number of times you want to perform the complete set of runs required by the design. Using replicates helps to separate error caused by a poor model fit from error caused by natural variation (i.e., experimental error).
Block on Replicates allows you to choose whether you will use each replicate of the design as a block. By blocking on replicates, you can account for "nuisance factors" (i.e., effects that are not of interest to the investigator) due to conditions that differ from one replicate of the design to another. For example, if the first replicate of the design is performed on Day 1, and the second is performed on Day 2, you could account for variation in the response due to the day. This option is available only if the number of replicates in the design is greater than 1.
Block Settings
Blocks allows you to specify the total number of blocks that will be used in the design. Blocks / Replicate (shown when you choose to block on replicates) allows you to specify the number of blocks that will be used per replicate. The more blocks you use in the design, the more potential nuisance factors you can account for. Note, however, that using blocks requires aliasing them with one or more effects.
Select a number of blocks from the drop-down list; the options available in this list depend on the type of design and the number of factors. Using 1 block in the entire design is equivalent to not using blocks.
With Taguchi OA designs, you must block on replicates to use blocks, and you can use at most 1 block per replicate.
Center Points / Block allows you to specify the number of center points that will be used per block. Center points are used primarily to help you determine if there is curvature in the relationship between the factors and the response. In addition, using several center points provides an estimate of pure error.
Block Values allows you to enter a name for each block.
Taguchi OA Settings
The options available in the Taguchi Design Type drop-down list will depend on the numbers of levels for each factor. For example, if all your factors have three levels, then you could choose the L9 (3^4) design, which uses nine runs to investigate up to 4 three-level factors. If some factors have two levels and the rest have four, then you could choose the L16 (2^9*4^2) design, which uses 16 runs to investigate up to 9 two-level factors and up to 2 four-level factors.
Click the View
Alias Table icon 
to see the
alias table for the selected Taguchi design type. The
table shows what aliases result from assigning factors
to particular columns in the orthogonal array.
Taguchi Column Indices allows you assign factors to columns of the selected orthogonal array. No two factors can have the same index.
The Specify Interaction Terms link opens a window that helps you assign factors to columns without aliasing any main effects or any interaction terms of interest. (See Specify Interaction Terms Window.)
Click Design Summary in the navigation panel to review the properties of your currently configured design. Some of these properties are also listed in the Design Information area on the control panel, and you can access the settings for those properties by clicking the links. (See Design Summary.)
Once you are satisfied with your settings, click the Build icon on the control panel to create the Data tab that contains the test "plan."
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