One day, early in my quality career, I was approached by my friend Wayne, the manager of our galvanizing plant.

 "Tom," he began, "I've really been pushing quality in my area lately, and everyone's involved. We're currently working on a problem with plating thickness. Your reports always show a 3-percent to 7-percent reject rate, and we want to drive that number down to zero."

 I, of course, was pleased. The galvanizing area had been the company's perennial problem child. "How can I help?" I asked.

 "We've been trying to discover the cause of the low thicknesses, but we're stumped. I want to show copies of the quality reports to the team so they can see what was happening with the process when the low thicknesses were produced."

 "No problem," I said, "I'll have them for you this afternoon."

 Wayne left, and I went to my galvanizing reports file. The inspection procedure called for seven light poles to be sampled and plotted each hour. Using the reports, I computed the daily average and standard deviation by hand (this was before the age of personal computers). Then, using a table of normal distribution areas, I found the estimated percent below the low specification limit. This number had been reported to Wayne and a number of others. As Wayne had said, the rate tended to be between 3 percent and 7 percent.

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