ECONOMIC DESIGN OF (X)over-bar CONTROL CHART UNDER DEWMA MODEL

In this paper, mathematical investigation has been made to study the effect of double exponentially weighted moving average (DEWMA) model on economic design of (X) over bar control chart. Formulae are derived for calculating the value of n and h when the characteristics of an item possess DEWMA model. A numerical example is derived to verify the performance of DEWMA model in presence of normality. The DEWMA charts working together with normality affects the control chart scheme when small to moderate shifts in the mean of the controlled parameter are expected. It is found that when shifts are uncertain the optimal design for DEWMA chart should be more conservative.