MODELLING ‐CHART UNDER NON‐NORMALITY AND INSPECTOR ERRORS

This paper investigates the effect of non‐normality errors on the economic design of x‐control charts. The measurable quality characteristic of the product is assumed to be non‐normally distributed random variable. The process is subject to a single assignable cause with exponentially distributed occurrence time. This assignable cause shifts the process from in‐control state to out‐of‐control state. The economic design of x‐chart involves optimal determination of the design parameters so as to minimize the expected total cost. The optimal value of the design parameters are obtained using a computerized search technique. Consequently, the effect of non‐normality parameters and errors on the design parameters and on the loss‐cost function is explained through numerical examples.