Adaptive CUSUM and EWMA charts with auxiliary information and variable sampling intervals for monitoring the process mean |
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Authors: | Abdul Haq Shareen Akhtar Michael Boon Chong Khoo |
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Affiliation: | 1. Department of Statistics, Quaid-i-Azam University, Islamabad, Pakistan;2. School of Mathematical Sciences, Universiti Sains Malaysia, Minden, Penang, Malaysia |
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Abstract: | The variable sampling interval (VSI) feature enhances the sensitivity of a control chart that is based on fixed sampling interval (FSI). In this paper, we enhance the sensitivities of the auxiliary information-based (AIB) adaptive Crosier cumulative sum (CUSUM) (AIB-ACC) and adaptive exponentially weighted moving average (EWMA) (AIB-AE) charts using the VSI feature when monitoring a mean shift which is expected to lie within a given interval. The Monte Carlo simulations are used to compute zero-state and steady-state run length properties of these control charts. It is found that the AIB-ACC and AIB-AE charts with VSI feature are uniformly more sensitive than those based on FSI feature. Real datasets are also considered to demonstrate the implementation of these control charts. |
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Keywords: | control charts process monitoring and control statistical quality control |
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