Track: Quality Control and Quality Management

Abstract

This research proposes an optimal Exponentially Weighted Moving Average (EWMA) control chart for monitoring the failure rate of buses in a transport company to improve the quality of service, avoid negative impacts and enhance the customers’ satisfaction. The charting parameters of the EWMA chart, including the weighting parameter and the control limit, are optimized to achieve the best detection effectiveness. The proposed control chart is compared with the optimal NP chart in terms of the Average Number of Failures (ANF) since the shift occurs until the control chart can detect it. Failure data were obtained from the company for the implementation of the control charts. The results of the comparative study reveal that the EWMA chart substantially outperforms the NP chart, especially for detecting small and moderate shifts. It is very beneficial for the company to use an effective monitoring tool to guarantee continuous improvement and a high standard of efficiency.