Economic Design of EWMA Standard Deviation Charts Using Variable Sampling Policy

In order to reduce the cost of the production cycle, the economic design of EWMA standard deviation charts with variable sampling interval (VSI) is discussed in this paper. First, the optimal values of the test parameters for the VSI EWMA standard deviation charts will be determined such that the expected total cost is minimized. Further, the genetic algorithms (GA) will be used to search for the optimal values of parameters of the VSI EWMA standard deviation chart, and an example is provided to illustrate the solution procedure. Finally, a sensitivity analysis is carried out to economic modal and the effect of model parameters on the solution of the economic design is obtained.