Abstract

GUTIERREZ, HUMBERTO. Bayesian Control Charts for Attributes and the Large Subgroup Size in p Chart. Rev.Colomb.Estad. [online]. 2006, vol.29, n.2, pp.163-180. ISSN 0120-1751.

The problems of the control charts for attributes are analyzed. In particular, it is seen that the traditional procedure to obtain the control limits has several difficulties: it does not incorporate the uncertainty in the estimate of the parameter of the distribution, it does not include the variation of the process, and the procedure requires a base period to obtain the control limits. Along this period it does not have a control chart to analyze the process. It is seen that these problems are solved applying Bayesian methods. It is described a sequential procedure to obtain the Bayesian control limits for p, np, c and u charts, from the first observation. This eliminates the necessity of the base period. Lastly it is analyzed the problem of the p chart when it is based on a large subgroup size and it is proposed a Bayesian solution for this problem.

Keywords : Quality control; Bayesian methods; Beta-binomial distribution; Poisson-gamma distribution.

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