It’s never enough to be skilled in DOE, FMEA, 8D, systematic root cause analysis, and other techniques. Instead, we must connect our skill with knowledge – knowledge of theory of variation. In the face of one type of variation, for example, systematic root cause analysis works like a hot knife through butter. In the face of a different type of variation, apply that technique at your peril!
The late Dr. W. Edwards Deming noted how the Taguchi loss function illustrates that it’s not necessary to achieve some precise optimum. But it also illustrates that increased variation will always result in increased waste, cost, and loss. Thus, the “bottom line” of Taguchi’s model is that variation is the enemy – because it will always generate loss.