Short Run SPC, Part 1 and Part 2 showed how to use zed charts and difference charts to track the underlying process while making different products. This part will illustrate both the robustness of the zed chart and an incorrect way of standardizing the data from the different products.

The robustness of process behavior charts

In this section we shall revisit the zed chart from the plant in Europe that was featured in Part One. We do this because, unlike the other examples in parts one and two, this process was being operated unpredictably. This unpredictability introduces some additional steps in the use of the ANOMmR chart. In addition, in retelling this story we shall also discover just how robust the process behavior chart is in practice.

Recall that three products labeled Red, Blue, and Green were produced in one production unit. The data are shown in figure 1 in production order.

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