An Improvement of the EM Algorithm for Finite Poisson Mixtures PDF Download
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Author: Dimitris Karlis
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Finite Poisson mixtures can be used in a variety of real applications to describe count data as they can describe situations where overdispersion relative to the simple Poisson model is present. They also admit a natural interpretation: the entire population is a mixture of k subpopulations each having a Poisson distribution giving rise to the k-finite Poisson distribution. Estimating the parameters of a k-finite Poisson mixture is not easy. However, the development of the EM algorithm for finite mixtures simplified the derivation of the maximum likelihood estimates. In this paper an improvement of the standard EM algorithm for finite Poisson mixtures is introduced. It is based on the result that one from the estimating equations for the Maximum Likelihood Estimates in the case of finite Poisson mixtures is the first moment equation. Hence, replacing one of the estimating equations by this simpler form help us considerably in reducing the labour and the cost of calculating the MLE. Tables verifying the results are also given.
Author: Dimitris Karlis
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Finite Poisson mixtures can be used in a variety of real applications to describe count data as they can describe situations where overdispersion relative to the simple Poisson model is present. They also admit a natural interpretation: the entire population is a mixture of k subpopulations each having a Poisson distribution giving rise to the k-finite Poisson distribution. Estimating the parameters of a k-finite Poisson mixture is not easy. However, the development of the EM algorithm for finite mixtures simplified the derivation of the maximum likelihood estimates. In this paper an improvement of the standard EM algorithm for finite Poisson mixtures is introduced. It is based on the result that one from the estimating equations for the Maximum Likelihood Estimates in the case of finite Poisson mixtures is the first moment equation. Hence, replacing one of the estimating equations by this simpler form help us considerably in reducing the labour and the cost of calculating the MLE. Tables verifying the results are also given.
Author: Dimitris Karlis
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
One of the estimating equations of the Maximum Likelihood Estimation method, for finite mixtures of the one parameter exponential family, is the first moment equation. This can help considerably in reducing the labor and the cost of calculating the Maximum Likelihood estimates. In this paper it is shown that the EM algorithm can be substantially improved by using this result when applied for mixture models. A short discussion about other methods proposed for the calculation of the Maximum Likelihood estimates are also reported showing that the above findings can help in this direction too.
Author: Dimitris Karlis
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The EM algorithm is a standard tool for maximum likelihood estimation in finite mixture models. The main drawbacks of the EM algorithm are its slow convergence and the dependence of the solution on both the stopping criterion and the initial values used. The problems referring to slow convergence and the choice of a stopping criterion have been dealt with in literature and the present paper deals with the initial value problem for the EM algorithm. The aim of this paper is to compare several methods for choosing initial values for the EM algorithm in the case of finite mixtures as well as to propose some new methods based on modifications of existing ones. The cases of finite normal mixtures with common variance and finite Poisson mixtures are examined through a simulation study.
Author: Geoffrey McLachlan
Publisher: John Wiley & Sons
ISBN: 047165406X
Category : Mathematics
Languages : en
Pages : 419
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Book Description
An up-to-date, comprehensive account of major issues in finitemixture modeling This volume provides an up-to-date account of the theory andapplications of modeling via finite mixture distributions. With anemphasis on the applications of mixture models in both mainstreamanalysis and other areas such as unsupervised pattern recognition,speech recognition, and medical imaging, the book describes theformulations of the finite mixture approach, details itsmethodology, discusses aspects of its implementation, andillustrates its application in many common statisticalcontexts. Major issues discussed in this book include identifiabilityproblems, actual fitting of finite mixtures through use of the EMalgorithm, properties of the maximum likelihood estimators soobtained, assessment of the number of components to be used in themixture, and the applicability of asymptotic theory in providing abasis for the solutions to some of these problems. The author alsoconsiders how the EM algorithm can be scaled to handle the fittingof mixture models to very large databases, as in data miningapplications. This comprehensive, practical guide: * Provides more than 800 references-40% published since 1995 * Includes an appendix listing available mixture software * Links statistical literature with machine learning and patternrecognition literature * Contains more than 100 helpful graphs, charts, and tables Finite Mixture Models is an important resource for both applied andtheoretical statisticians as well as for researchers in the manyareas in which finite mixture models can be used to analyze data.
Author: Dominik Liebl
Publisher:
ISBN:
Category :
Languages : en
Pages : 80
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Book Description
Author: Sylvia Fruhwirth-Schnatter
Publisher: CRC Press
ISBN: 0429508247
Category : Computers
Languages : en
Pages : 522
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Book Description
Mixture models have been around for over 150 years, and they are found in many branches of statistical modelling, as a versatile and multifaceted tool. They can be applied to a wide range of data: univariate or multivariate, continuous or categorical, cross-sectional, time series, networks, and much more. Mixture analysis is a very active research topic in statistics and machine learning, with new developments in methodology and applications taking place all the time. The Handbook of Mixture Analysis is a very timely publication, presenting a broad overview of the methods and applications of this important field of research. It covers a wide array of topics, including the EM algorithm, Bayesian mixture models, model-based clustering, high-dimensional data, hidden Markov models, and applications in finance, genomics, and astronomy. Features: Provides a comprehensive overview of the methods and applications of mixture modelling and analysis Divided into three parts: Foundations and Methods; Mixture Modelling and Extensions; and Selected Applications Contains many worked examples using real data, together with computational implementation, to illustrate the methods described Includes contributions from the leading researchers in the field The Handbook of Mixture Analysis is targeted at graduate students and young researchers new to the field. It will also be an important reference for anyone working in this field, whether they are developing new methodology, or applying the models to real scientific problems.
Author: Ruochu Gao
Publisher:
ISBN:
Category : Conditional expectations (Mathematics)
Languages : en
Pages : 152
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Book Description
Author: Geoffrey J. McLachlan
Publisher: John Wiley & Sons
ISBN: 0470191600
Category : Mathematics
Languages : en
Pages : 399
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Book Description
The only single-source——now completely updated and revised——to offer a unified treatment of the theory, methodology, and applications of the EM algorithm Complete with updates that capture developments from the past decade, The EM Algorithm and Extensions, Second Edition successfully provides a basic understanding of the EM algorithm by describing its inception, implementation, and applicability in numerous statistical contexts. In conjunction with the fundamentals of the topic, the authors discuss convergence issues and computation of standard errors, and, in addition, unveil many parallels and connections between the EM algorithm and Markov chain Monte Carlo algorithms. Thorough discussions on the complexities and drawbacks that arise from the basic EM algorithm, such as slow convergence and lack of an in-built procedure to compute the covariance matrix of parameter estimates, are also presented. While the general philosophy of the First Edition has been maintained, this timely new edition has been updated, revised, and expanded to include: New chapters on Monte Carlo versions of the EM algorithm and generalizations of the EM algorithm New results on convergence, including convergence of the EM algorithm in constrained parameter spaces Expanded discussion of standard error computation methods, such as methods for categorical data and methods based on numerical differentiation Coverage of the interval EM, which locates all stationary points in a designated region of the parameter space Exploration of the EM algorithm's relationship with the Gibbs sampler and other Markov chain Monte Carlo methods Plentiful pedagogical elements—chapter introductions, lists of examples, author and subject indices, computer-drawn graphics, and a related Web site The EM Algorithm and Extensions, Second Edition serves as an excellent text for graduate-level statistics students and is also a comprehensive resource for theoreticians, practitioners, and researchers in the social and physical sciences who would like to extend their knowledge of the EM algorithm.
Author: D. M. Titterington
Publisher:
ISBN:
Category : Mathematics
Languages : en
Pages : 264
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Book Description
In this book, the authors give a complete account of the applications, mathematical structure and statistical analysis of finite mixture distributions.
Author: Maya R. Gupta
Publisher: Now Publishers Inc
ISBN: 1601984308
Category : Computers
Languages : en
Pages : 87
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Book Description
Introduces the expectation-maximization (EM) algorithm and provides an intuitive and mathematically rigorous understanding of this method. Theory and Use of the EM Algorithm is designed to be useful to both the EM novice and the experienced EM user looking to better understand the method and its use.
