27.2 Interpretation of Results

In this example, the resulting significant effects are the main effect A (Gas Flow = 9) and the interaction AB (Gas Flow × Intensity = −6,5). Factor C (speed of the production chain) is inert.

Since factors A and B interact, it is necessary to draw an interaction plot to interpret the results. To do so, choose Stat > DOE > Factorial > Factorial Plots.

Use first the option Interaction Plot.

Use now the option Cube Plot. The displayed dialog box looks similar to the previous one.

Minitab draws very small numbers in the plot when using Cube Plot. If you want to use this plot in reports or presentations, it is recommended that you edit it by increasing the font size.

The two interaction plots are equivalent; from one you can build the other (the following plots have been edited to increase the font size of the numbers):

The best result is obtained with a gas flow of 12 l/min and an intensity of 230 A. Note that if you ever need, whatever the ...

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