Circular Outliers Detection Using a Mixture of Von Mises Distributions

Document Type : Original Paper

Authors

1 University Lecturer / Tarbiat Modares University

2 Tarbiat Modares University

Abstract

Circular data are typical examples of directional data with a specific regular period‎. ‎Because the presence of outliers leads to invalid statistical inferences on the parameters of the circular regression models‎, ‎their prevalence in analyzing these models requires particular attentions‎. ‎There are different approaches for modeling the structure of the data set with outliers in which using the mixture models is among the most important ones‎. ‎As a new idea‎, ‎to study the methods in determining the outlier data and to employ the mixture model of Von Mises distribution are considered in this paper‎. ‎The EM algorithm is utilized to estimate the parameters of these models‎. ‎The performance of the proposed models is investigated using some simulation studies, and then the confusion matrix is considered to evaluate the accuracy of fitting models. ‎Also‎, ‎the proposed methods are applied to analyze a real data set‎, ‎related to the wave directional analysis in the Bushehr province in Iran.

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[1] Mardia, K. V. (1972), Statistics of Directional Data, London: Academic Press.
[2] Jammalamadaka, S. R. and SenGupta, A. (2001), Topics in Circular Statistics, Singapore: World Scientific.
[3] Gould, A. L. (1969), A Regression Technique for Angular Variates, Biometrics, 25, 683-700.
[4] Laycock, P. J. (1975), Optimal Design: Regression Models for Directions, Biometrika, 62, 305-311. [5] Sarma, Y., and Jammalamadaka, S. (1993), Circular Regression, Statistical Science and Data Analysis, 109-128. [6] Rivest, L. P. (1997), A Decentred Predictor for Circular-Circular Regression, Biometrika, 84, 717-726.
[7] Lund, U. (1999), Least Circular Distance Regression for Directional Data, Journal of Applied Statistics, 26, 723-733.
[8] Downs, T. D. and Mardia, K. V. (2002), Circular Regression, Biometrika, 89, 683-697. [9] Hussain, A. G., Fieller, N. R. J. and Stillman, E. C. (2004), Linear Regression for Circular Variables with Application to Directional Data, Journal of Applied Science and Technology, 9, 1-6.
[10]
Hussain, A. G., Abdullah, N. A. and Mohamed, I. (2010), A Complex Linear Regression Model, Sains Malaysian, 39, 491–494. [11] Collett, D. (1980), Outliers in Circular Data, Journal of Applied Statistics, 29, 50-57.
[12] Bagchi, P. and Guttman, I. (1990), Spuriosity and Outliers in Directional Data, Journal of Applied Statistics, 17, 341-350. [13] Abuzaid, A. H., Mohamed, I. B. and Hussain, A. G. (2009), A New Test of Discordancy in Circular Data, Communications in StatisticsSimulation and Computation, 38, 682-691.
[14] Abuzaid, A., Mohamed, I., Rambli, A. and Hussain, A. G. (2011), COVRATIO Statistic for Simple Circular Regression Model, Chiang Mai Journal of Science, 38, 321-330.