Economic statistical design for and S2 control charts: A markov chain approach

Over-adjustment to a process may result in shifts in process mean, process variance, or both, ultimately affecting the quality of products. A statistically constrained model is developed for the joint economic statistical design of and S2 control charts to control both process mean and variance. The objective is to determine the design parameters of the control charts, which minimize the total quality control cost. A Markov chain approach is used to derive the model. Application of the model is demonstrated through a numerical example.