Evaluating the product quality level under multiple L-type quality characteristics

One of the most critical issues encountered in the area of quality engineering is the selection of an appropriate quality loss function to relate key quality characteristics of a product to its quality performance. The loss function can be used to evaluate the quality loss in terms of monetary units that enables managers to quantify unobservable costs. It aids manufacturers to evaluate quality improvement projects more rigorously, hence, the choice of paths for quality enrichment depends on the type of loss function. Although several multivariate quality loss functions have been proposed, these models only considered the-nominal-the-best (N-type) quality characteristics. The effect of other types of quality characteristics was not addressed. In this paper, a cost model is proposed to evaluate the quality level of a product with multiple the-larger-the-better (L-type) quality characteristics. An example with two quality characteristics is given to illustrate the application.