Volume 29, Issue 5, 2020
DOI: 10.24205/03276716.2020.1196
Improving the Performance of EWMA mean chart with use of Two Auxiliary Variables
Abstract
Control chart is magnificent monitoring technique applied in tracing undesired variation in the manufacturing and services processes. Quality practitioners are always in search of cost-effective monitoring model to produce high quality products. Auxiliary information-based procedures provide unbiased and more efficient estimate about the process mean. The exponentially weighted moving average (EWMA) scheme based on regression estimator using two auxiliary variables is proposed for efficient monitoring of the process mean in this study. The performance of the proposed design is reported under the collinear and non-collinear cases of the two auxiliary variables. The sensitivity of the proposed chart is compared with classical EWMA, single use of auxiliary EWMA, classical homogeneously weighted moving average (HWMA) and single auxiliary information based HWMA control charts. The comparison reveals the superiority of the proposed chart over its competitors. An application is also included to support the theory
Keywords
Auxiliary characteristics; Average run length; Efficient control chart; Multicollinearity; Regression estimator