When I talk to quality professionals about how they use statistics, one tool they mention again and again is design of experiments, or DOE. I’d never even heard the term before I started getting involved in quality improvement efforts, but now that I’ve learned how it works, I wonder why I didn’t learn about it sooner. If you need to find out how several factors are affecting a process outcome, DOE is the way to go.

Somewhere in school you probably learned, like I did, that when you do an experiment you need to hold all the factors constant except for the one you’re studying. That seems simple enough, until you hit a situation where you have many factors that you want to study at the same time. Not only would studying each factor one at a time be very expensive and time-consuming, you also wouldn’t get any information about how the different factors might affect each other.

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