Computing Average Run Lengths of Exponential EWMA Charts

Abstract

An exponential EWMA chart is useful for monitoring the mean β of interarrival times of nonconforming items in many manufacturing processes. A program is presented for determining the average run length (ARL) profiles of one-sided or two-sided EWMA charts. The ARL is computed using an exact procedure. The ARL's over a range of β's can be obtained given the chart parameters. The ARL profiles provide a more comprehensive understanding of the performance of a chart.

• Average Run Length
• Exponential Distribution
• Poisson Distribution
• Statistical Process Control

Additional information

Notes on contributors

F. F. Gan

Dr. Gan is an Associate Professor in the Department of Statistics and Applied Probability. He is also a Member of ASQ. His email address is [email protected]

T. C. Chang

Mr. Chang is a Process Control Specialist in the Department of Memory Products.