1. A Laplace-based model with flexible tail behavior.
- Author
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Tortora, Cristina, Franczak, Brian C., Bagnato, Luca, and Punzo, Antonio
- Subjects
- *
MONTE Carlo method , *LAPLACE distribution , *OUTLIER detection , *EXPECTATION-maximization algorithms - Abstract
The proposed multiple scaled contaminated asymmetric Laplace (MSCAL) distribution is an extension of the multivariate asymmetric Laplace distribution to allow for a different excess kurtosis on each dimension and for more flexible shapes of the hyper-contours. These peculiarities are obtained by working on the principal component (PC) space. The structure of the MSCAL distribution has the further advantage of allowing for automatic PC-wise outlier detection – i.e., detection of outliers separately on each PC – when convenient constraints on the parameters are imposed. The MSCAL is fitted using a Monte Carlo expectation-maximization (MCEM) algorithm that uses a Monte Carlo method to estimate the orthogonal matrix of eigenvectors. A simulation study is used to assess the proposed MCEM in terms of computational efficiency and parameter recovery. In a real data application, the MSCAL is fitted to a real data set containing the anthropometric measurements of monozygotic/dizygotic twins. Both a skewed bivariate subset of the full data, perturbed by some outlying points, and the full data are considered. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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