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This paper presents an R package EMMIXcskew for the fitting of the canonical fundamental skew t-distribution (CFUST) and finite mixtures of this distribution (FM-CFUST) via maximum likelihood (ML). The CFUST distribution provides a flexible…

Computation · Statistics 2017-02-10 Sharon X. Lee , Geoffrey J. McLachlan

We show how the expectation-maximization (EM) algorithm can be applied exactly for the fitting of mixtures of general multivariate skew t (MST) distributions, eliminating the need for computationally expensive Monte Carlo estimation. Finite…

Methodology · Statistics 2012-09-06 S. X. Lee , G. J. McLachlan

In this paper, we present an algorithm for the fitting of a location-scale variant of the canonical fundamental skew t (CFUST) distribution, a superclass of the restricted and unrestricted skew t-distributions. In recent years, a few…

Methodology · Statistics 2014-02-03 Sharon X. Lee , Geoffrey J. McLachlan

Finite mixture models have been widely used for the modelling and analysis of data from heterogeneous populations. Maximum likelihood estimation of the parameters is typically carried out via the Expectation-Maximization (EM) algorithm. The…

Computation · Statistics 2016-06-08 Sharon X Lee , Kaleb L Lee , Geoffrey J McLachlan

Finite mixtures of skew distributions provide a flexible tool for modelling heterogeneous data with asymmetric distributional features. However, parameter estimation via the Expectation-Maximization (EM) algorithm can become very…

Computation · Statistics 2016-08-10 Sharon X Lee , Kaleb L Leemaqz , Geoffrey J McLachlan

Finite mixture models have been widely used to model and analyze data from a heterogeneous populations. Moreover, data of this kind can be missing or subject to some upper and/or lower detection limits because of the restriction of…

This is an extended version of the paper Lee and McLachlan (2014b) with simulations and applications added. This paper introduces a finite mixture of canonical fundamental skew t (CFUST) distributions for a model-based approach to…

Methodology · Statistics 2014-05-06 Sharon X. Lee , Geoffrey J. McLachlan

Analysis of matrix-variate data is becoming increasingly common in the literature, particularly in the field of clustering and classification. It is well-known that real data, including real matrix-variate data, often exhibit high levels of…

Methodology · Statistics 2024-07-30 Abbas Mahdavi , Narayanaswamy Balakrishnan , Ahad Jamalizadeh

Finite mixture of skew distributions have emerged as an effective tool in modelling heterogeneous data with asymmetric features. With various proposals appearing rapidly in the recent years, which are similar but not identical, the…

Methodology · Statistics 2013-05-29 Sharon X. Lee , Geoffrey J. McLachlan

In this study, we propose a robust mixture regression procedure based on the skew t distribution to model heavy-tailed and/or skewed errors in a mixture regression setting. Using the scale mixture representation of the skew t distribution,…

Statistics Theory · Mathematics 2017-06-12 Fatma Zehra Doğru , Olcay Arslan

Normal mean-variance mixture distributions are widely applied to simplify a model's implementation and improve their computational efficiency under the Maximum Likelihood (ML) approach. Especially for distributions with normal mean-variance…

Methodology · Statistics 2015-06-18 Thanakorn Nitithumbundit , Jennifer S. K. Chan

In this paper, we propose finite mixtures of multivariate skew Laplace distributions to model both skewness and heavy-tailedness in the heterogeneous data sets. The maximum likelihood estimators for the parameters of interest are obtained…

Statistics Theory · Mathematics 2017-02-03 Fatma Zehra Doğru , Y. Murat Bulut , Olcay Arslan

Expectation-Maximization (EM) algorithm is a widely used iterative algorithm for computing (local) maximum likelihood estimate (MLE). It can be used in an extensive range of problems, including the clustering of data based on the Gaussian…

Machine Learning · Statistics 2023-03-28 Pierre Houdouin , Esa Ollila , Frederic Pascal

The Expectation-Maximization (EM) algorithm is a fundamental tool in unsupervised machine learning. It is often used as an efficient way to solve Maximum Likelihood (ML) estimation problems, especially for models with latent variables. It…

Quantum Physics · Physics 2020-07-08 Iordanis Kerenidis , Alessandro Luongo , Anupam Prakash

Handling missing data is a major challenge in model-based clustering, especially when the data exhibit skewness and heavy tails. We address this by extending the finite mixture of scale mixtures of multivariate skew-normal (FMSMSN) family…

Methodology · Statistics 2025-07-29 Jason Pillay , Cristina Tortora , Antonio Punzo , Andriette Bekker

Mixture Markov Model (MMM) is a widely used tool to cluster sequences of events coming from a finite state-space. However the MMM likelihood being multi-modal, the challenge remains in its maximization. Although Expectation-Maximization…

Optimization and Control · Mathematics 2026-04-16 Priyam Das , Deborshee Sen , Debsurya De , Jue Hou , Zahra S. H. Abad , Nicole Kim , Zongqi Xia , Tianxi Cai

Any clustering algorithm must synchronously learn to model the clusters and allocate data to those clusters in the absence of labels. Mixture model-based methods model clusters with pre-defined statistical distributions and allocate data to…

Machine Learning · Computer Science 2022-10-04 Dumindu Tissera , Kasun Vithanage , Rukshan Wijesinghe , Alex Xavier , Sanath Jayasena , Subha Fernando , Ranga Rodrigo

Expectation maximisation (EM) is an unsupervised learning method for estimating the parameters of a finite mixture distribution. It works by introducing "hidden" or "latent" variables via Baum's auxiliary function $Q$ that allow the joint…

Machine Learning · Computer Science 2022-05-19 Graham W. Pulford

Nonlinear mixed effects models have received a great deal of attention in the statistical literature in recent years because of their flexibility in handling longitudinal studies, including human immunodeficiency virus viral dynamics,…

Methodology · Statistics 2021-09-28 Fernanda L. Schumacher , Dipak K. Dey , Victor H. Lachos

We study a class of weakly identifiable location-scale mixture models for which the maximum likelihood estimates based on $n$ i.i.d. samples are known to have lower accuracy than the classical $n^{- \frac{1}{2}}$ error. We investigate…

Statistics Theory · Mathematics 2021-11-17 Raaz Dwivedi , Nhat Ho , Koulik Khamaru , Martin J. Wainwright , Michael I. Jordan , Bin Yu
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