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np-Charts for attribute control

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Bibliographic Details
Summary:In this article, we introduce charts for attribute control considering the number of defective items, named np‐charts. These charts are preferable over charts for proportion (p) of defective items, named p‐charts, when the sample size (n) remains constant for all subgroups. The benefits of using np‐charts over p‐charts are: an easier interpretation and the fact that no calculation is required for each sample result. We provide a review of the basic issues related to np‐charts and some recent ideas on the topic based on life distributions. In addition, we discuss an implementation of np‐charts in the R software by using examples with data on attributes and lifetimes.
Main Authors:Leiva, Victor
Other Authors:Oliveira, Amilcar
Subject:Binomial distribution Life distributions np‐charts R software
Year:2015
Country:Portugal
Document type:book part
Access type:restricted access
Associated institution:Universidade Aberta
Language:English
Origin:Repositório Aberto da Universidade Aberta
Description
Summary:In this article, we introduce charts for attribute control considering the number of defective items, named np‐charts. These charts are preferable over charts for proportion (p) of defective items, named p‐charts, when the sample size (n) remains constant for all subgroups. The benefits of using np‐charts over p‐charts are: an easier interpretation and the fact that no calculation is required for each sample result. We provide a review of the basic issues related to np‐charts and some recent ideas on the topic based on life distributions. In addition, we discuss an implementation of np‐charts in the R software by using examples with data on attributes and lifetimes.

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