Moderate distribution with six sigma control chart for range

Abstract

Fuzzy set theory is a powerful mathematical tool for evaluating the vagueness-related uncertainty that can be expressed linguistically in certain situations. Control charts are the most effective and unobtrusive way of statistical process control. Many times, data is gathered in quantitative form; nevertheless, there are many qualitative aspects that cannot be stated numerically, such as appearance, smoothness, and colour, among others. In this research, we develop a six sigma-based fuzzy control limit for a range with a moderate distribution.