Monitoring censored lifetime data with a weighted-likelihood scheme
针对删失寿命数据监控中现有方法控制性能不佳的问题，提出一种基于加权似然比检验的COWL控制图，结合指数加权移动平均方案，在模拟和碳纤维断裂强度实例中表现出更强的变化检测能力。
Lifetime experiments are common in many research areas and industrial applications. Recently, process monitoring for lifetime observations has received increasing attention. However, some existing methods are inadequate as neither their in control (IC) nor out of control (OC) performance is satisfactory. In addition, the challenges associated with designing robust and flexible control schemes have yet to be fully addressed. To overcome these limitations, this article utilizes a newly developed weighted likelihood ratio test, and proposes a novel monitoring strategy that automatically combines the likelihood of past samples with the exponential weighted sum average scheme. The proposed Censored Observation-based Weighted-Likelihood (COWL) control chart gives desirable IC and OC performances and is robust under various scenarios. In addition, a self-starting control chart is introduced to cope with the problem of insufficient reference samples. Our simulation shows a stronger power in detecting changes in the censored lifetime data using our scheme than using other alternatives. A real industrial example based on the breaking strength of carbon fiber also demonstrates the effectiveness of the proposed method. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 631–646, 2017