Lingyun, Zhang; Lai C. D.; Govindaraju K.; Bebbington M. - In: Economic Quality Control 19 (2004) 1, pp. 23-27
Using a counter example, we show that the formula for computing the Average Run Lengths (ARL) of a moving average control chart (MA) in Wetherill and Brown (1991) is incorrect. However, we conjecture that the formula may provide an upper bound for the ARL of a moving average control chart.