Exact Results for Variable Sampling Interval Shewhart Control Charts with Runs Rules for Switching Between Sampling Interval Lengths
The exact expressions for the performance measures for variable sampling interval charts in which runs rules are used for switching between the sampling interval lengths are developed. The methods presented are general and can be applied to other Shewhart control charts. The effects of different runs rules on the performances of the charts are evaluated through numerical comparisons. Recommendations of some runs rules are made as per the requirements of the process monitoring.