Confidence interval of generalized Taguchi index
In quality control, such as other statistical problems, we may confront imprecise concepts. One case is a situation in which specification limits are two fuzzy sets. In such a fuzzy environment, the product is not qualified with a two valued Boolean view, but to some degree depending on the quality level of the product and the strictness of the decision maker. This matter can be cause to a justified judgment in decision making on manufacturing processes. The generalized process capability indices C similar to(p), C similar to(pk) and C similar to(pm) can be helpful and necessary for measuring the fuzzy quality in an in-control process. In this paper, the generalized Taguchi index C similar to(pm) is proposed to provide an assessment of the ability of the fuzzy process to be clustered around the target value. Considering fuzzy specification limits we present four approximate 100(1 - gamma)% confidence intervals for the generalized process capability index C similar to(pm) in this paper. Then, we obtain several fast computable 100(1 - gamma)% confidence intervals for C similar to(pm), where the fuzzy specification limits are linear, normal or elliptic. An industrial example is given to show the performance of the proposed method.
confidence interval fuzzy quality fuzzy limits taguchi process capability index