Economic design of (X)over-bar control charts for non-normal data using variable sampling policy

Bai and Lee (Int. J. Prod. Econ. 54 (1998) 57) developed an economic model for a variable sampling interval (VSI),$(X) over bar $ control chart. In developing the model they considered the process data with normality property in their design methodology. However, in practice the validity of the normal assumption is doubted in many situations. In this paper, an alternative cost model that employs the Burr distribution is proposed to deal with the economic design of the VSI $(X) over bar $ -charts when the normality assumption of process data is unacceptable. Besides non-normal process data, this model is also suitable for normally distributed data. Consequently, it is able to provide a more general application. The design procedure and sensitivity analysis on the process parameters, cost parameters, and degrees of skewness and kurtosis of population are illustrated through an industrial application. (C) 2003 Elsevier B.V. All rights reserved.