Abstract One widely used control chart, the -chart, is based on the assumption that means of samples drawn from the process are normally distributed. When the normality assumption is not valid, control chart users may choose from several different courses of action. These include using Box-Cox...

Abstract The reduction of run length variability has received little attention in the statistical process control literature. This note proposes a modification of the signal rule for the EWMA control chart resulting in a reasonable reduction of run length variability.

Abstract Most of the commonly used control charts for variables have been developed under the assumption that the observations are coming from a normal population. One of them is ‘Group Runs’ GR control chart to detect shifts in the process mean proposed by Gadre and Rattihalli (Economic...

Abstract A comprehensive economic cost function is derived for a modified variable sample size and sampling interval (MVSSI) chart. As a variable sample size and sampling interval, a variable sample size, a variable sampling interval, and a static charts are particular cases of an MVSSI chart,...

Abstract This paper describes the application of simple quality control charts to monitor the traffic intensity of single server queues, a still uncommon use of what is arguably the most successful statistical process control tool. These charts play a vital role in the detection of increases in...

Abstract The traffic intensity (ρ) is a vital parameter of queueing systems because it is a measure of the average occupancy of a server. Consequently, it influences their operational performance, namely queue lengths and waiting times. Moreover, since many computer, production and...