Economic Design of X Control Charts for Monitoring a First Order Autoregressive Process

• Autor(a) principal: Costa, Antonio F. B.
• Data de Publicação: 2010
• Outros Autores: Claro, Fernando Antonio Elias
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Brazilian Journal of Operations & Production Management (Online)
• Texto Completo: https://bjopm.org.br/bjopm/article/view/V7N2A1
• topic: Autocorrelation; First Order Autoregressive Model; Economic Design; Control Chart; Statistical Process Control

In this paper we deal with the economic design of an X control chartused to monitor a quality characteristic whose observations fit to a first orderautoregressive model. The Duncan cost model is used to select the controlchart parameters, namely the sample size (n), the sampling interval (h) andthe control limit coefficient (k), that lead to the optimal monitoring cost. Wefound that the autocorrelation has an adverse effect on the chart’s power, onthe false alarm risk and on the cost. It also increases n and h and decreasesk. To counteract this undesired effect we considered setting up the subgroupsusing non-sequential observations. It is shown that this sampling strategysignificantly reduces the monitoring cost.