Guaranteed conditional design of the median chart with estimated parameters

作者：Hu, XueLong^*; Castagliola, Philippe

来源：Quality and Reliability Engineering International, 2017, 33(8): 1873-1884.

DOI：10.1002/qre.2152

• average average run length
• bootstrap method
• estimated parameters
• median chart
• standard deviation of average run length

A common assumption for most control charts is the fact that the process parameters are supposed to be known or accurately estimated from Phase I samples. But, in practice, this is not a realistic assumption and the process parameters are usually estimated from a very limited number of samples that, in addition, may contain some outliers. Recently, a median chart with estimated parameters has been proposed to overcome these issues and it has been investigated in terms of the unconditional Average Run Length (ARL). As this median chart with estimated parameters does not take the Phase I between-practitioners variability into account, in this paper, we suggest to revisit it using the Standard Deviation of the ARL as a measure of performance. The results show that this Standard Deviation of the ARLbased median chart actually requires a much larger amount of Phase I data than previously recommended to sufficiently reduce the variation in the chart performance. Due to the practical limitation of the number of the Phase I data, the bootstrap method is recommended as a good alternative approach to define new dedicated control chart parameters.

• 出版日期2017-12
• 单位南京邮电大学