A New Procedure of Clustering Based on Multivariate Outlier Detection

Abstract

Clustering is an extremely important task in a wide variety of ap- plication domains especially in management and social science research. In this paper, an iterative procedure of clustering method based on multivariate outlier detection was proposed by using the famous Mahalanobis distance. At rst, Mahalanobis distance should be calculated for the entire sample, then using T 2 -statistic x a UCL. Above the UCL are treated as outliers which are grouped as outlier cluster and repeat the same procedure for the remaining inliers, until the variance-covariance matrix for the variables in the last cluster achieved singularity. At each iteration, multivariate test of mean used to check the discrimination between the outlier clusters and the inliers. Moreover, multivariate control charts also used to graphically visual- izes the iterations and outlier clustering process. Finally multivariate test of means helps to rmly establish the cluster discrimination and validity. This paper employed this procedure for clustering 275 customers of a famous two- wheeler in India based on 19 dierent attributes of the two wheeler and its company. The result of the proposed technique conrms there exist 5 and 7 outlier clusters of customers in the entire sample at 5% and 1% signicance level respectively.