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Ordered Samples Control Charts for Ordinal Variables
Author(s) -
Franceschini Fiorenzo,
Galetto Maurizio,
Varetto Marco
Publication year - 2005
Publication title -
quality and reliability engineering international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 62
eISSN - 1099-1638
pISSN - 0748-8017
DOI - 10.1002/qre.614
Subject(s) - ordinal data , control chart , ordinal scale , sample (material) , sample space , statistics , statistical process control , mathematics , sample size determination , scale (ratio) , variable (mathematics) , variance (accounting) , ordinal optimization , computer science , ordinal regression , process (computing) , geography , mathematical analysis , chemistry , cartography , accounting , business , operating system , chromatography
The paper presents a new method for statistical process control when ordinal variables are involved. This is the case of a quality characteristic evaluated by an ordinal scale. The method allows a statistical analysis without exploiting an arbitrary numerical conversion of scale levels and without using the traditional sample synthesis operators (sample mean and variance). It consists of a different approach based on the use of a new sample scale obtained by ordering the original variable sample space according to some specific ‘dominance criteria’ fixed on the basis of the monitored process characteristics. Samples are directly reported on the chart and no distributional shape is assumed for the population (universe) of evaluations. Finally, a practical application of the method in the health sector is provided. Copyright © 2005 John Wiley & Sons, Ltd.