Definition of taguchi method of quality control

a method of controlling quality, developed by Genich Taguchi, a past winner of the Deming Award, that emphasizes robust quality design and the quality loss function (QLF). Taguchi claims that quality is greatly determined at the design level. In addition to quality control in production, he emphasizes quality control in four other functions: (1) product planning, (2) product design, (3) process design, and (4) production service after purchase. Further, Taguchi's QLF quantitatively measures the success or failure of quality control. The traditional view is that any product that measures within the upper and lower specification limits is "good," and a product outside the limits is "bad." In contrast, the QLF presumes that any deviation from the target specification is important because it means economic losses for the customer. Furthermore, the economic losses increase quadratically as the actual value deviates from the target value.