Industrial Engineering Journal ›› 2020, Vol. 23 ›› Issue (3): 145-153.doi: 10.3969/j.issn.1007-7375.2020.03.019

• Practice & Application • Previous Articles     Next Articles

A LOF Algorithm-Based Multivariate Process Monitoring Scheme for Mixed-Type Data

ZHANG Qiaowei, LI Yanting   

  1. School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
  • Received:2019-01-29 Published:2020-07-04

Abstract: A LOF algorithm-based mixed-type data control chart (Mixed-type data Local Outlier Factor Control Chart, MLOF) was proposed to solve the monitoring problem of mixed-type data with ordinal and nominal variables. During the process of detecting changes in process variables, MLOF control chart fully considers the information entropy of nominal categorical variables and the rank of ordinal categorical variables. It measures the abnormality of observation point based on density. The performance of MLOF control chart and the existing mixed-type data control chart on outlier detection was compared using a simulation case based on credit card application data set and a real data case based on German credit card data set. The simulation case included 30 monitoring scenarios. The results show MLOF control chart performs best in 57% of these scenarios. The real data case also verifies that the MLOF control chart is more suitable for the mixed-type data monitoring process with large data volume and complicated clustering situation.

Key words: multivariable mixed-type data, information entropy, distance metric, LOF algorithm, MLOF control chart

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