Process behavior charts are the interface between your data and your brain. But you have to begin by making a choice about which type of chart to use. You can either plot the individual values themselves, or you can organize your data into rational subgroups and plot the subgroup averages. This paper will discuss the issues involved and provide guidelines for when to use each chart.

The role of process behavior charts

Your data almost always possess some sort of time-order sequence. In most cases this order will be linked to the operation of some underlying process. Yet most statistical techniques ignore this time-order sequence. Process behavior charts use this temporal order to characterize the behavior of these underlying processes. In this regard they are fundamentally different from virtually all other statistical procedures. Rather than trying to fit some type of mathematical model to the data, they use the time order in the data to characterize the underlying process as being either predictable or unpredictable.

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