ENBIS: European Network for Business and Industrial Statistics

Bayesian modeling for fraction nonconforming

23 September 2009, 11:15 – 11:35

Abstract

Submitted by

Panagiotis Tsiamyrtzis

Authors

Panagiotis Tsiamyrtzis

Affiliation

Dept. of Statistics, Athens University of Economics and Business

Abstract

We consider a process for which one or more quality characteristics are used to classify the outcome as acceptable or not. As a result we obtain attribute data of Binomial type distribution with unknown "success probability" that expresses the percent of nonconforming. In this work we focus in modeling dynamically this probability and detect (in an online fashion) of whether it shifts to higher values (i.e. we have process degradation) or not. The modeling will be based on a sequentially updated mixture of Beta distributions that will allow the process readings to contribute as they become available, making the approach particularly attractive in case of Phase I, or in general short run, attribute data. Decision making and prediction issues will be provided.


Keywords:
Bayesian SPC by attributes, Beta mixtures, Phase I, short runs.

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