An approach for quality control chart appropriateness evaluation based on desirability functions

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Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Industrial Engineering, Turkey

Approval Date: 2016

Student: SIDIKA TUNÇ

Supervisor: GÜLSER KÖKSAL

Abstract:

Quality control charts are among the oldest and most powerful tools in statistical process control. Several control charts have been developed for specific needs and characteristics of processes. However, their proper implementation requires expert knowledge about statistics and properties of these charts. In this study, an effective approach is developed to evaluate appropriateness of control charts for the process to be monitored and the process owner. This approach can be used to recommend the most appropriate control chart to a novice process owner. The chart evaluation problem is formulated as a multi-criteria decision making problem, and desirability functions are utilized for its solution. The evaluation criteria are identified and the desirability functions are constructed based on knowledge from literature and experts. The approach is developed and tested for commonly used X̄-R, X̄-S, I-MR, I-MR-R and Exponentially Weighted Moving Average (EWMA) variable control charts; and its parameters are fine-tuned by statistical experimentation and optimization.