Few process improvement topics generate more questions or may be least understood than design of experiments (DOE). This is regrettable as DOE is probably one of the most important activities—after the charter definition—that a manager/Black Belt will be performing during the Six Sigma process.
This purpose of this paper is to demystify DOE by framing the topic in terms managers can readily understand. I will describe it in business terms, show you how to design and conduct a basic DOE, and finally, discuss how to interpret the results of DOE. To reinforce the concepts, I will walk you through an actual DOE I recently conducted with AT&T. Finally, I’ll present some key lessons learned about DOE.

DOE overview
What is DOE? Why is it used? What are its benefits? Where does it fit within the Six Sigma process? DOE is much more than a set of experiments as the name may imply. The DOE activity generally occurs sometime during the analyze and improve phases of the define-measure-analyze-improve-implement-control (DMAIIC) process. DMAIIC is a rational decision-making process for improving existing processes. DOE also occurs during the analyze and improve phases of the define-measure-analyze-design-verify (DMADV) process. DMADV is a rational decision-making process for building new processes (See figure 1).

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