ENBIS-17 in Naples

9 – 14 September 2017; Naples (Italy) Abstract submission: 21 November 2016 – 10 May 2017

Phase I Performance of Control Charts under Temporally Random Contamination of Observations

13 September 2017, 10:30 – 10:50


Submitted by
Murat Caner Testik
Murat Caner Testik (Hacettepe University), Christian H. Weiß (Helmut Schmidt University), Yesim Koca (Hacettepe University), Ozlem Muge Testik (Hacettepe University)
Several researches have been performed to study the effects of parameter estimation in a Phase I study of control charts. However, these studies mostly considered that reference sets of observations used in estimation of parameters are from an in-control process and accordingly studied the effects of sampling variability on the Phase II performance of control charts. In this study, a different approach is taken and it is considered that the reference sets of observations used in Phase I studies may be contaminated. To detect the contaminated samples representing out-of-control process states and to estimate process parameters, Shewhart control charts for sample averages and sample standard deviation were simulated for normally distributed observations. Iterative implementation of control limit revisions were performed as recommended in text books. Contaminations were generated as random shifts that may affect none, one or more of the observations in a sample. Results of performance metrics such as the number of iterations, true and false alarm percentages are discussed under several scenarios that may be useful in practical settings.

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