On designing a new Tukey-EWMA control chart for process monitoring

• Published in: International journal of advanced manufacturing technology Vol. 82; no. 1-4; pp. 1 - 23
• Main Authors: Khaliq, Qurat-Ul-Ain, Riaz, Muhammad, Ahmad, Shabbir
• Format: Journal Article
• Language: English
• Published: London Springer London 01-01-2016; Springer Nature B.V
• Subjects: Aerospace industry; CAE) and Design; Computer-Aided Engineering (CAD; Control charts; CUSUM charts; Engineering; Industrial and Production Engineering; Mechanical Engineering; Media Management; Normality; Original Article; Process parameters; Process planning; Skewed distributions; Tukey control chart; Extra quadratic loss; EWMA-TCC; Exponentially weighted moving average chart; Average run length; Industrial production index; Non-normality
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-015-7289-6

Exponentially weighted moving average (EWMA) and cumulative sum (CUSUM) charts are used to detect smaller shifts in process parameters. The usual EWMA and CUSUM charts depend on the normality assumption for a better detection ability. This study proposes an efficient EWMA control chart based on the spirit of Tukey control chart, especially designed for skewed distributions. The performance of the proposed and the competing charts is measured using different length properties such as average run length (ARL), standard deviation of run length (SDRL), and median run length (MDRL). We have observed that the proposed chart is quite efficient at detecting process shifts of smaller magnitude, especially for skewed distributions. For practical considerations, the proposed chart is implemented at aerospace manufacturing data on industrial production index.