Bayesian Monitoring of Times Between Events: The Shewhart tr-Chart

• Autores: Nirpeksh Kumar, Subha Chakraborti
• Localización: Journal of quality technology: A quarterly journal of methods applications and related topics, ISSN 0022-4065, Vol. 49, Nº. 2, 2017, págs. 136-154
• Idioma: inglés
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• Resumen

  • The traditional (frequentist) tr -chart is a Shewhart-type chart useful for monitoring times between events (interarrival times) following an exponential distribution. This problem often arises in high-yield processes where the defect rate is low and hence the conventional attribute charts such as the c-chart and the u-chart are often ineffective. We consider this problem under the Bayesian framework and propose a Bayesian tr - chart when the exponential rate parameter is unknown. The Bayesian tr -chart is a Shewhart-type chart that incorporates parameter uncertainty via a prior and a posterior distribution, unlike the traditional tr -chart. The control limits are constructed from the predictive distribution of a plotting statistic. The performance of the proposed chart is evaluated and comparisons are made with the traditional tr -chart. The Bayesian chart is seen to be advantageous in certain situations. An illustrative example is given and a summary and conclusions are offered.