Most control charts used to jointly monitor time between event and amplitude assume that the process shift size is known,but in actual production these control charts for specific shift sizes suffer from monitoring performance degra-dation because the shift size of the data is unknown.To this end,this paper constructs adaptive smoothing parameters for the EWMA statistic based on unbiased estimates of time between event and amplitude,and proposes a new adaptive Max-EWMA control chart for joint monitoring time between event and amplitude(referred to as Max-AEWMA chart)by combi-ning the structural features of the Max-EWMA statistic.Simulations show that the proposed control chart is consistently better than the existing Max-EWMA control chart when monitoring different size of shift in time between event and ampli-tude.For example,when a=4,b=1,λE=0.01,δa=0.59,δλE=0.73,Max-AEWMA's ARL1=4.94,Max-EWMA'sARL1=4.94.The paper also concludes with an empirical analysis to verify the superiority of the method.
关键词
自适应/Max-EWMA/幅值/统计过程控制
Key words
adaptive/Max-EWMA/magnitude/statistical process control
万方数据