I was working with a client to create their business’s critical performance measures the other day, and one of the managers said, “We should set the target higher than we want it—you know, aim high to hit low.” This set off one of my rants, and I thought I would share it with you.

When I worked as an engineer, we would get requests from customers for tighter-than-standard specification limits. I’d do a little control and capability analysis to see if our process was capable of meeting the requested limits. If so, then we would approve the change. If not, I could estimate the amount that would go out of spec over time, and we could calculate the increased cost of scrap due to setting the tighter limits. In some cases, we would go ahead with the change, knowing that it would cost us more money, either because the scrap cost was small or because there was some other reason to accept the loss. (Knowing what I know now about the Taguchi Loss Function, we probably lost money on most of these changes due to the increased nonscrap losses.)

One day I called a customer to say that we wouldn’t be able to meet their tighter limits. “I’m sorry,” I said, “but our process just is not capable of it. Actually, I don’t think there is a process out there that is capable of it.”

“Oh, we know,” he said, “those specs are a lot tighter than we really need.

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