A comparison study of three non-parametric control charts to detect shift in location parameters

Abstract

Control charts are used as a statistical process control or SPC tool to identify the presence of assignable cause of variation in the process. Despite immense use and acceptability of parametric control charts, non-parametric control charts are an emerging area of recent development in the theory of SPC. The main advantage of non-parametric control charts is that they do not require any knowledge about the underlying distribution of the variable. In this work, we have summarized the different non-parametric control charts for controlling location from a literature survey, viz. control charts based on the sign test, control charts based on the Hodges–Lehmann estimator and control charts based on the Mann–Whitney statistic and compared their efficiency to detect the shift in location while in out of the control state under different situations and identified the best method under the prevailing situation.