(2023-05-23) Chin What To Think When Looking At A Chart

Cedric Chin: What To Think When Looking at a Chart. ...one question that I've had over the course of this series is: if understanding variation is so important and process behaviour charts are so good at helping you understand variation in your data, why aren't they more widely used? And I think I have a partial answer:

I recorded a podcast interview with Eric Nehrlich yesterday where we talked about his work on Google’s revenue forecasting team

when you’re working with a process that is exposed to so many exogenous factors, it actually becomes more trouble than it’s worth to use an XmR chart.

Google’s revenues suddenly blipped in the months before the bank meltdowns in the 2007 global financial crisis, and also how their revenue per query experienced a sudden dip when Michael Jackson died.

Donald Wheeler repeatedly says, in both Understanding Variation and Making Sense of Data, that “the purpose of data is insight, which means the best analysis is the simplest analysis that gives you needed insight.”

If you don’t need an XmR chart to tell you a change has occured, or if an XmR chart is too difficult for your context, don’t use an XmR chart.

once you “get to right” in one area, it is starts to become easier to “get to right” in another