Performance of T² Chart over 𝑥̅ Chart for Monitoring the Process Mean: A Simulation Study

Md. Belal Hossain and Mohammad Shahed Masud

Abstract: In real life we observe that there are many situations in which the simultaneous monitoring or control of two or more related quality characteristics is necessary. In such situations we can use univariate control charts to each individual quality characteristics but these control charts can lead to erroneous conclusions. Multivariate methods that consider the quality characteristics jointly are required. The most familiar multivariate process monitoring and control procedure is the Hotelling T² control chart for monitoring the process mean simultaneously. It is a direct analog of the univariate Shewhart  control chart. In this paper, using simulation study we show that if the quality characteristics are related then for monitoring the mean of the process Hotelling T² control chart performs better than Shewhart  control chart.

Keywords: Quality characteristics; Shewhart control chart; multivariate control chart; detection rate of out of control signal.

Pages: 498 – 512 | Full PDF Paper