One-sided EWMA charts for monitoring time between events using the three-region approach

This paper applies the three-region approach to TBE (time-between-events) charts and proposes monitoring procedures tailored to this framework.The three-region approach partitions the parameter space into an in-control region, an out-of-control region, and an indifference region, providing a more realistic representation of practical decision-making.Within this framework, we develop three TBE charting procedures: Shewhart, CUSUM (cumulative sum), and EWMA (exponentially weighted moving average) charts.In particular, this paper focuses on two modified EWMA chart procedures designed to enhance monitoring performance.All procedures employ onesided lower control limits to effectively detect process degradation.The performance of the proposed procedures is evaluated through extensive simulation studies, and their relative effectiveness is systematically compared.