I’ve been privileged to work in the statistical-software industry for the last 10 years, and frequently I receive phone calls from professionals who need information or guidance on statistical methods. Overwhelmingly, they call with excellent questions. Their interest and enthusiasm are exciting, and I’m grateful for the opportunity to help them.

I receive painful, distressing phone calls as well. In fact, I get the same inquiring phone call on a frighteningly consistent basis. It’s a frustrating discussion, but at the same time it is curious and (in a statistically macabre way) a bit funny. When they ask the question, I usually tilt my head and squint my uncomprehending eyes like a dog who has just heard a strange sound. That phone call goes something like this:

Caller: “Hi, Doug. Thanks for taking my call. I have some questions about control charts and control limits.”

Doug: “Great! I’m glad you called. What’s your question?”

Caller: “Well, sometimes those dratted plot points fall outside of my chart’s control limits. We hate it when that happens. Windows pop up in our software, charts turn red, and operators gotta enter some kinda codes. Our operators don’t like it when their charts turn red. That sure is bothersome.”

Doug: (Tilts head, squints eyes, and looks intently at his dog). “Uh, OK. What’s your question?”

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