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Monitoring process variation using modified EWMA
Author(s) -
Saghir Aamir,
Aslam Muhammad,
Faraz Alireza,
Ahmad Liaquat,
Heuchenne Cedric
Publication year - 2020
Publication title -
quality and reliability engineering international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 62
eISSN - 1099-1638
pISSN - 0748-8017
DOI - 10.1002/qre.2576
Subject(s) - ewma chart , control chart , chart , smoothing , x bar chart , statistics , computer science , moving average , standard deviation , statistical process control , process (computing) , variance (accounting) , step detection , mathematics , accounting , filter (signal processing) , business , computer vision , operating system
A new control chart, namely, modified exponentially weighted moving average (EWMA) control chart, for monitoring the process variance is introduced in this work by following the recommendations of Khan et al. 15 The proposed control chart deduces the existing charts to be its special cases. The necessary coefficients, which are required for the construction of modified EWMA chart, are determined for various choices of sample sizes and smoothing constants. The performance of the proposed modified EWMA is evaluated in terms of its run length (RL) characteristics such as average RL and standard deviation of RL. The efficiency of the modified EWMA chart is investigated and compared with some existing control charts. The comparison reveals the superiority of proposal as compared with other control charts in terms of early detection of shift in process variation. The application of the proposal is also demonstrated using a real‐life dataset.