A Newly Modified Extended EWMA Chart for Efficient Process Mean Monitoring

The exponentially weighted moving average (EWMA) chart is an effective tool in statistical process control (SPC) for detecting small process shifts, yet its sensitivity remains insufficient for the precision demands of modern manufacturing. To address this, researchers have proposed a modified EWMA (MEWMA) chart that incorporates an adjustment constant and an extended EWMA (EEWMA) chart that applies dual smoothing parameters. Building on these approaches, this study introduces a modified extended EWMA (MEEWMA) chart that integrates adjustment and dual-smoothing mechanisms. Simulation studies show that the MEEWMA chart achieves lower average run length (ARL) values compared with the traditional EWMA, MEWMA, and EEWMA charts, particularly under small process mean shifts. These findings demonstrate that the MEEWMA chart offers improved sensitivity, flexibility, and robustness, enabling faster detection of small process mean changes.