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Your search keyword '"Khoo, Michael B.C."' showing total 2 results
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2 results on '"Khoo, Michael B.C."'

1. A variable sampling interval EWMA t chart with auxiliary information – A robustness study in the presence of estimation error.

Author

Ng, Peh Sang, Khoo, Michael B.C., Saha, Sajal, and Lee, Ming Ha

Subjects
QUALITY control charts, SAMPLING errors, MOVING average process, NUMERICAL analysis, STANDARD deviations
Abstract

This article proposes the variable sampling interval (VSI) exponentially weighted moving average (EWMA) t chart for the process mean using auxiliary information (AI) (denoted as the VSI EWMA t -AI chart). The proposed chart allows different sampling intervals to be adopted based on prior process quality. The average time to signal (ATS) and expected average time to signal (EATS) criteria are used to evaluate the performance of the proposed chart. Numerical analyses are conducted and the results show that the proposed VSI EWMA t -AI chart surpasses the EWMA t -AI chart in the detection of all sizes of shifts in the process mean when there are no changes (or estimation error) in the process standard deviation. Additionally, the proposed VSI EWMA t -AI chart is found to be more robust than the VSI EWMA X ¯ -AI chart when there are changes in the process standard deviation. [ABSTRACT FROM AUTHOR]

Published
2022
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2. Synthetic control chart with curtailment for monitoring shifts in fraction non-conforming

Author

Haridy, Salah, Chong, Nger Ling, Khoo, Michael B.C., Shamsuzzaman, Mohammad, and Castagliola, Philippe

Abstract

The integration of the curtailment method with control charts considerably improves the detection speed by signalling an out-of-control condition prior to the inspection of the whole sample. To date, few research works have focused on the incorporation of the curtailment method to improve the performance of control charts. Thus, this paper incorporates the curtailment approach with the synthetic chart to propose a synthetic with curtailment (Curt_Syn) control chart for detecting upward shifts in the fraction non-conforming, p. We compare the newly developed Curt_Syn chart with the synthetic, exponentially weighted moving average (EWMA), cumulative sum (CUSUM), EWMA with curtailment (Curt_EWMA), and CUSUM with curtailment (Curt_CUSUM) charts. From an overall perspective, the results reveal that the Curt_Syn chart surpasses the synthetic chart by 38% under various conditions. For all pshifts, the Curt_Syn chart outperforms the CUSUM and EWMA charts. When the pshift is large, the Curt_Syn chart is superior to the Curt_CUSUM and Curt_EWMA charts. To demonstrate the implementation of the Curt_Syn chart, an illustrative example is provided. [Received: 30 April 2019; Accepted: 7 April 2021]

Published
2022
Full Text
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