Publicações > Artigos em Revistas Internacionais

On valid signals in joint schemes for the process mean and variance

Ralha, T.; Morais, M. C. ; Oliveira, M. Rosário

Economic Quality Control, volume 30, issue 2 (2015), 99-110
http://www.degruyter.com/dg/viewarticle.fullcontentlink:pdfeventlink/$002fj$002feqc.2015.30.issue-2$002feqc-2015-0001$002feqc-2015-0001.pdf?t:ac=j$002feqc.2015.30.issue-2$002feqc-2015-0001$002feqc-2015-0001.xml

Joint schemes for the process mean and the variance are essential to determine if unusual variation in the location and spread of a quality characteristic has occurred.
This paper comprises a systematic study on the phenomena of misleading, unambiguous and simultaneous signals while dealing with Shewhart and EWMA joint schemes for the process mean and the variance of a normally distributed quality characteristic.
Examples have been added to illustrate how the R statistical software can be used to assess the performance of joint schemes in practice, namely when it comes to the occurrence of those valid signals.