Abstract. We developed type-2 fuzzy percentile-based standard PCIs for non-normal data via Clements’ method. For modeling
uncertainty and imprecision of data, interval type-2 fuzzy sets are utilized. To prove usefulness and applicability of the proposed
type-2 fuzzy percentile-based standard PCIs, a numerical illustration is performed for the data randomly generated from Lognormal
distribution. The results show that in comparison with their crisp types, the proposed type-2 fuzzy percentile-based standard
PCIs for non-normal processes are more informative, sensitive and flexible to evaluate the process performance of the industrial
processes.
Keywords: Process capability index, clements’ method, interval type-2 fuzzy set, non-normal processes