Simultaneous monitoring of time between events and their multivariate magnitude

Document Type : Research Paper

Authors

1 Department of Industrial Engineering, Faculty of Engineering, Shahed university, Tehran, Iran

2 Department of Industrial Engineering , Faculty of Engineering, Shahed University, Tehran, Iran

10.22070/jqepo.2025.18419.1271

Abstract

Monitoring the time between events without accounting for their magnitudes is an impractical approach. This paper discusses the monitoring of the time between events (TBEs) and their multivariate magnitude (M). The paper explores control charts for the magnitude of events in a multivariate setting, focusing on situations where the magnitude of events has two dimensions. Two statistics are presented in this paper for the simultaneous monitoring of the time between events and the multivariate magnitude. The first statistic is a standardized EWMAZ, which is based on the Shewhart-EWMA approach. The second statistic is a set of three standardized single EWMAs, with each one used for monitoring TBEs and the two dimensions of magnitude (TSEWMA). The performance of these two statistics is evaluated by considering different shifts in the mean of TBE and magnitude under three distinct shift parameter values. The results confirm the effectiveness of these two statistics across various conditions.

Keywords

Journal of Quality Engineering and Production Optimization

Articles in Press, Accepted Manuscript
Available Online from 13 May 2025

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