An ARL-unbiased c-chart

作者：Paulino Sofia; Morais Manuel Cabral^*; Knoth Sven

来源：Quality and Reliability Engineering International, 2016, 32(8): 2847-2858.

DOI：10.1002/qre.1969

• average run length
• randomized and uniformly most powerful unbiased tests

In statistical process control (SPC), it is usual to assume that counts have a Poisson distribution. The non-negative, discrete, and asymmetrical character of a control statistic with such a distribution and the value of its target mean may prevent the quality control practitioner to deal with a c-chart with a pre-specified in-control average run length (ARL) or the ability to control not only increases but also decreases in the mean of those counts in a timely fashion. Furthermore, the c-charts proposed in the SPC literature tend to be ARL-biased, in the sense that some out-of-control ARL values are larger than the in-control ARL. In this paper, we explore the notions of randomized and uniformly most powerful unbiased tests to eliminate the bias of the ARL function of the c-chart.

• 出版日期2016-12