Two-Way Analysis of Variance with Interaction
Effects to be entered: A, B, A*B
1. In the Select Columns list, select two nominal or ordinal effects, A and B.
2. Select Macros > Full Factorial.
Or:
1. In the Select Columns list, select two nominal or ordinal effects, A and B.
2. Click Add.
3. In the Select Columns list, select A and B again and click Cross.
Example of Two-Way Analysis of Variance with Interaction
You have data about the yield of popcorn and are interested in whether the type of popcorn and the size of the batch have an effect on yield.
1. Select Help > Sample Data Library and open Popcorn.jmp.
2. Select Analyze > Fit Model.
3. In the Select Columns list, select yield and click Y.
4. In the Select Columns list, select popcorn and batch.
5. Select Macros > Full Factorial.
Figure 2.10 Fit Model Window for Two-Way Analysis of Variance with Interaction
Figure 2.11 shows a profiler plot of the fit for this example. To obtain this plot, click Run in the Fit Model window shown in Figure 2.10. Then, click the Response yield red triangle and select Factor Profiling > Profiler.
In the top plot, popcorn is set to gourmet, and in the bottom plot, it is set to plain. Note how the predicted values for the settings of batch depend on the type of popcorn. This is a consequence of the interaction between popcorn and batch.
Figure 2.11 Model Fit for a Two-Way Analysis of Variance with Interaction
