Title: Online monitoring of auto correlated linear profiles via mixed model

Authors: Paria Soleimani; Ali Narvand; Sadigh Raissi

Addresses: Department of Industrial Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran ' Department of Industrial Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran ' Department of Industrial Engineering, Islamic Azad University, South Tehran Branch, Tehran, Iran

Abstract: In statistical quality control a profile can be characterised by a given mathematical function between a quality characteristic and one or more explanatory process variables. Most existing control charts in the literature have been proposed for profile monitoring with the independence assumption of the observation within profiles. However in certain situation, this assumption can be violated. The present study focused on phase II of a linear profile monitoring and extends Jensen et al. (2008)'s work in applying linear mixed models on the presence of autocorrelation within profiles. Three methods namely Hotteling T², multivariate exponential weighted moving average (MEWMA) control chart and multivariate cumulative sum (MCUSUM) control chart are discussed and their performances are compared in term of average run length (ARL). These techniques are illustrated with a real data set taken from an agriculture field.

Keywords: multivariate process monitoring; linear profile monitoring; mixed models; modelling; multivariate cumulative sum; MCUSUM; multivariate exponential weighted moving average; MEWMA; HottelingT²; auto correlation; average run length; statistical quality control; SQC; control charts; agriculture.

DOI: 10.1504/IJMTM.2013.058901

International Journal of Manufacturing Technology and Management, 2013 Vol.27 No.4/5/6, pp.238 - 250

Accepted: 26 Jul 2013
Published online: 29 Apr 2014 *

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