Economic–statistical design of adaptive moving average (A–MA) control charts

This research proposes a method for economic–statistical design of adaptive moving average (A–MA) charts. The basic idea of the A–MA chart is to accumulate previous samples selectively in order to increase the sensitivity. The A–MA chart is a kind of adaptive chart such as the variable sampling size (VSS) chart. A major advantage of the A–MA chart over the VSS chart is that it is easy to maintain rational subgroups by using the fixed sampling size. A steady state cost rate function is constructed based on Lorenzen and Vance model. The cost rate function is optimized with respect to five design parameters. Computational experiments show that the A–MA chart is superior to the VSS chart as well as to the Shewhart chart in the economic–statistical sense.