Selecting the right control chart starts by knowing something about what you want the chart to say about the process—what questions do you want the chart to answer? Another way to look at this is to ask yourself, “Why am I collecting data on this part?” The answers to these questions will provide necessary information to determine the sampling strategy, sample size, and any special needs that would require implementing special processing options that extend the function of traditional charts. This column will address sample size, target charting, and multiple process streams with variables data. There are other considerations and data types that will be discussed in future columns.

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