On Efficient Monitoring of Weibull Lifetimes Using Censored Median Hybrid DEWMA Chart
Algorithm
1: ARL0 computation for HDEWMA.
(1)
Initiate the algorithm by fixing ,, and group size. Estimate the parameter using phase-I data if it is unknown.
(2)
Replace the censored observations with the CM value, i.e., transform the data into Gij and compute the CM-HDEWMA statistics for given m and n. Take the quantile point, where is prespecified.
(3)
Repeat Step 2 w times and compute the average of the upper control limits obtained by taking the quantile of the monitoring statistic, which will result in UCL for the CM-HDEWMA chart.
(4)
Plot the values of CM-HDEWMA monitoring statistic with respect to the subgroup numbers. Record the sample number at which the monitoring statistic falls outside the control limit.
(5)
Repeat Step 4 a large number of times and calculate the mean of the subgroup numbers at which the process first time crossed the UCL. This will result in ARL0 if the subgroups are generated from the in-control process.
