An Outlier Detection Methodology with Consideration for an Inefficient Frontier
Johnson, A.L. and L.F. McGinnis, 2008. “Outlier Detection in Two-Stage Semiparametric DEA Models.” European Journal of Operational Research 187(2): 629-635.
27 Pages Posted: 3 Aug 2006 Last revised: 23 Feb 2018
Date Written: July 1, 2006
Abstract
In the use of peer group data to assess individual, typical or best practice performance, the effective detection of outliers is critical for achieving useful results, particularly for two-stage analyses. In the DEA-related literature, prior work on this issue has focused on the efficient frontier as a basis for detecting outliers. An iterative approach to deal with the potential for one outlier to mask the presence of another has been proposed but not demonstrated. This paper proposes using both the efficient frontier and the inefficient frontier to identify outliers and thereby improve the accuracy of second stage results in two-stage nonparametric analysis. The iterative outlier detection approach is implemented in a leave-one-out method using both the efficient frontier and the inefficient frontier and demonstrated in a two-stage semi-parametric bootstrapping analysis of a classic data set. The results show that the conclusions drawn can be different when outlier identification includes consideration of the inefficient frontier.
Keywords: Data envelopment analysis, productivity, inefficient frontier, outlier detection
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