Summary
The paper presents our experience with identifying and verifying outlying data points.
Firstly we recall the grand tour method implemented in a dynamic graphics environment and endowed with dynamically changing concentration ellipses and count plots — as proposed by Bartkowiak & Szustalewicz (1997). The method permits to select and identify some data points as suspected outliers. Next we propose to carry out a sort of classification of the found outliers by performing cluster analysis based on angular similarities of the suspected outliers. The procedure returns bundles of data vectors similar with respect to their outlyingness.
The considerations are illustrated with the Milk container data, analyzed formerly, a.o. by Atkinson (1994) and Muruzábal and Muñoz (1997).





Similar content being viewed by others
References
Asimov, D. (1985), ‘The grand tour: A tool for viewing multidimensional data’, SIAM J. of Scientific and Statistical Computations 6, 128–143.
Atkinson, A.C. (1994), ‘Fast very robust methods for the detection of multiple outliers’, Journal of the American Statistical Association 89, 1329–1339.
Atkinson, A.C., & Mulira, H.M., (1993), ‘The stalactite plot for the detection of outliers’, Statistics and Computing 3, 27–35.
Bartkowiak, A. (1999), ‘Some modern techniques for viewing multivariate data’, XXXIeJournées de Statistique, 17–21 Mai 1999, Résumés, Grenoble, France, 527–530.
Bartkowiak, A. & Szustalewicz, A. (1997), ‘Detecting outliers by a grand tour’, Machine Graphics & Vision 6(4), 486–505.
Bartkowiak, A. & Szustalewicz, A. (1998), ‘Watching steps of a grand tour implementation’, Machine Graphics & Vision 7(3), 655–680.
Billor, N., Hadi, A.S. & Velleman, P. (2000), ‘BACON: Blocked adaptive computationally efficient outlier nominators’, Computational Statistics & Data Analysis, (in press).
Gnanadesikan, J. (1997), Methods for Statistical Data Analysis of Multivariate Observations Wiley, New York. 2nd Edition (1st Edition 1977)
Huh, M.Y. & Kim, K. (1997), ‘Visualization of multidimensional data using modifications of grand tour’, Journal of Computational and Graphical Statistics submitted.
Muruzábal, J. & Muñoz, J. (1997), ‘On the visualization of outliers via self-organizing maps’, Journal of Computational and Graphical Statistics 6, 355–382.
Rocke, D.M. & Woodruff, D.L. (1996), ‘Identification of outliers in multivariate data’, Journal Journal of the American Statistical Association 91, 1047–1061.
Swayne, D., Cook, D. & Buja, A. (1991), ‘Xgobi: interactive dynamic graphics in the x window system with a link to S’, in ‘ASA Proceedings of the Section on Statistical Graphics’, pp. 1–8.
Tierney, L. (1990), LISP-STAT, An Object-Oriented Environment for Statistical Computing and Dynamic Graphics, John Wiley & Sons.
Wegman, E.J., Poston, W.L. & Solka, J.L. (1998), Image grand tour. Technical Report no. 150, The Center for Computational Statistics, George Mason University, April 1998, pp. 1–9.
Author information
Authors and Affiliations
Additional information
Supported in part by the Polish Research Committee KBN grant no. 8 T11 C031 16
Rights and permissions
About this article
Cite this article
Bartkowiak, A., Szustalewicz, A. Outliers — finding and classifying which genuine and which spurious. Computational Statistics 15, 3–12 (2000). https://doi.org/10.1007/s001800050031
Published:
Issue Date:
DOI: https://doi.org/10.1007/s001800050031