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Nonparametric Bayesian Models Based On Asymmetric Gaussian Distributions
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Book Synopsis Nonparametric Bayesian Models Based on Asymmetric Gaussian Distributions by : Ziyang Song
Download or read book Nonparametric Bayesian Models Based on Asymmetric Gaussian Distributions written by Ziyang Song and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Data clustering is a fundamental unsupervised learning approach that impacts several domains such as data mining, computer vision, information retrieval, and pattern recognition. Various clustering techniques have been introduced over the years to discover the patterns. Mixture model is one of the most promising techniques for clustering. The design of mixture models hence involves finding the appropriate parameters and estimating the number of clusters in the data. The Gaussian mixture model has especially shown good results to tackle this problem. However, the Gaussian assumption is not ideal for modeling asymmetrical data. For achieving an accurate approximation, I investigate the asymmetric Gaussian distribution which is capable of modeling asymmetric data. A prevalent challenge researchers face when applying mixture models is the correct identification of the adequate number of mixture components to model the data at hand. Hence, in this thesis, I propose statistical algorithms based on asymmetric Gaussian mixture models. I also present novel Bayesian inference frameworks to estimate parameters and learn model structure. Here, I thoroughly investigate the Bayesian inference framework, including Markov chain Monte Carlo and variational inference approaches, to learn appropriate model structure and precisely estimate parameters. I also incorporate feature selection within the frameworks to choose relevant features set and avoid noisy influence from uninformative features. Furthermore, I investigate nonparametric hierarchical models by introducing Dirichlet process and Pitman-Yor process.
Book Synopsis Nonlinear Mixture Models: A Bayesian Approach by : Tatiana V Tatarinova
Download or read book Nonlinear Mixture Models: A Bayesian Approach written by Tatiana V Tatarinova and published by World Scientific. This book was released on 2014-12-30 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book, written by two mathematicians from the University of Southern California, provides a broad introduction to the important subject of nonlinear mixture models from a Bayesian perspective. It contains background material, a brief description of Markov chain theory, as well as novel algorithms and their applications. It is self-contained and unified in presentation, which makes it ideal for use as an advanced textbook by graduate students and as a reference for independent researchers. The explanations in the book are detailed enough to capture the interest of the curious reader, and complete enough to provide the necessary background material needed to go further into the subject and explore the research literature.In this book the authors present Bayesian methods of analysis for nonlinear, hierarchical mixture models, with a finite, but possibly unknown, number of components. These methods are then applied to various problems including population pharmacokinetics and gene expression analysis. In population pharmacokinetics, the nonlinear mixture model, based on previous clinical data, becomes the prior distribution for individual therapy. For gene expression data, one application included in the book is to determine which genes should be associated with the same component of the mixture (also known as a clustering problem). The book also contains examples of computer programs written in BUGS. This is the first book of its kind to cover many of the topics in this field.
Book Synopsis Modeling Non-gaussian Time-correlated Data Using Nonparametric Bayesian Method by : Zhiguang Xu
Download or read book Modeling Non-gaussian Time-correlated Data Using Nonparametric Bayesian Method written by Zhiguang Xu and published by . This book was released on 2014 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: We further extend our models to the non-Gaussian longitudinal analysis setting. We model an observed within-subject response series as a transformation from a latent Gaussian series. The latent series specifies the within-subject dependence structure and the transformation function specifies marginal distribution of response variable. Similar to CTAR models, a marginal distribution of the response variable has a nonparametric Bayesian prior distribution and is therefore flexible in shape. We conduct simulations and study a 100km-race real dataset where the response variable is noticeably non-Gaussian. The data analysis demonstrates the advantage of copula-transformed models' performance in model fitting and prediction compared with the Gaussian-based models when the data is truly non-Gaussian and when the mean function is correctly specified. We also study the situations where the mean function shifts in the out-of-sample data. We find that the model's predictive performance for individuals is impacted by the shifts. The copula-transformed models are more sensitive to the shift than the Gaussian-based models. We also study the predictive performance of the contrasts. The models' predictive performance remains fairly robust to the shifts, and the copula-transformed models outperform the Gaussian-based models in contrast predictions. The proposed method can be extended in many directions, including using other transformation functions (e.g., a transformation using Polya tree prior).
Book Synopsis Bayesian Nonparametric Data Analysis by : Peter Müller
Download or read book Bayesian Nonparametric Data Analysis written by Peter Müller and published by Springer. This book was released on 2015-06-17 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews nonparametric Bayesian methods and models that have proven useful in the context of data analysis. Rather than providing an encyclopedic review of probability models, the book’s structure follows a data analysis perspective. As such, the chapters are organized by traditional data analysis problems. In selecting specific nonparametric models, simpler and more traditional models are favored over specialized ones. The discussed methods are illustrated with a wealth of examples, including applications ranging from stylized examples to case studies from recent literature. The book also includes an extensive discussion of computational methods and details on their implementation. R code for many examples is included in online software pages.
Book Synopsis Bayesian Nonparametrics by : Nils Lid Hjort
Download or read book Bayesian Nonparametrics written by Nils Lid Hjort and published by Cambridge University Press. This book was released on 2010-04-12 with total page 309 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bayesian nonparametrics works - theoretically, computationally. The theory provides highly flexible models whose complexity grows appropriately with the amount of data. Computational issues, though challenging, are no longer intractable. All that is needed is an entry point: this intelligent book is the perfect guide to what can seem a forbidding landscape. Tutorial chapters by Ghosal, Lijoi and Prünster, Teh and Jordan, and Dunson advance from theory, to basic models and hierarchical modeling, to applications and implementation, particularly in computer science and biostatistics. These are complemented by companion chapters by the editors and Griffin and Quintana, providing additional models, examining computational issues, identifying future growth areas, and giving links to related topics. This coherent text gives ready access both to underlying principles and to state-of-the-art practice. Specific examples are drawn from information retrieval, NLP, machine vision, computational biology, biostatistics, and bioinformatics.
Book Synopsis Bayesian Nonparametrics by : J.K. Ghosh
Download or read book Bayesian Nonparametrics written by J.K. Ghosh and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the first systematic treatment of Bayesian nonparametric methods and the theory behind them. It will also appeal to statisticians in general. The book is primarily aimed at graduate students and can be used as the text for a graduate course in Bayesian non-parametrics.
Book Synopsis Bayesian Learning Frameworks for Multivariate Beta Mixture Models by : Mahsa Amirkhani
Download or read book Bayesian Learning Frameworks for Multivariate Beta Mixture Models written by Mahsa Amirkhani and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixture models have been widely used as a statistical learning paradigm in various unsupervised machine learning applications, where labeling a vast amount of data is impractical and costly. They have shown a significant success and encouraging performance in many real-world problems from different fields such as computer vision, information retrieval and pattern recognition. One of the most widely used distributions in mixture models is Gaussian distribution, due to its characteristics, such as its simplicity and fitting capabilities. However, data obtained from some applications could have different properties like non-Gaussian and asymmetric nature. In this thesis, we propose multivariate Beta mixture models which offer flexibility, various shapes with promising attributes. These models can be considered as decent alternatives to Gaussian distributions. We explore multiple Bayesian inference approaches for multivariate Beta mixture models and propose a suitable solution for the problem of estimating parameters using Markov Chain Monte Carlo (MCMC) technique. We exploit Gibbs sampling within Metropolis-Hastings for learning parameters of our finite mixture model. Moreover, a fully Bayesian approach based on birth-death MCMC technique is proposed which simultaneously allows cluster assignments, parameters estimation and the selection of the optimal number of clusters. Finally, we develop a nonparametric Bayesian framework by extending our finite mixture model to infinity using Dirichlet process to tackle the model selection problem. Experimental results obtained from challenging applications (e.g., intrusion detection, medical, etc.) confirm that our proposed frameworks can provide effective solutions comparing to existing alternatives.
Author :Sylvia Frühwirth-Schnatter Publisher :Springer Science & Business Media ISBN 13 :0387357688 Total Pages :506 pages Book Rating :4.3/5 (873 download)
Book Synopsis Finite Mixture and Markov Switching Models by : Sylvia Frühwirth-Schnatter
Download or read book Finite Mixture and Markov Switching Models written by Sylvia Frühwirth-Schnatter and published by Springer Science & Business Media. This book was released on 2006-11-24 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: The past decade has seen powerful new computational tools for modeling which combine a Bayesian approach with recent Monte simulation techniques based on Markov chains. This book is the first to offer a systematic presentation of the Bayesian perspective of finite mixture modelling. The book is designed to show finite mixture and Markov switching models are formulated, what structures they imply on the data, their potential uses, and how they are estimated. Presenting its concepts informally without sacrificing mathematical correctness, it will serve a wide readership including statisticians as well as biologists, economists, engineers, financial and market researchers.
Book Synopsis Bayesian Learning of Asymmetric Gaussian-Based Statistical Models Using Markov Chain Monte Carlo Techniques by : Shuai Fu
Download or read book Bayesian Learning of Asymmetric Gaussian-Based Statistical Models Using Markov Chain Monte Carlo Techniques written by Shuai Fu and published by . This book was released on 2018 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: A novel unsupervised Bayesian learning framework based on asymmetric Gaussian mixture (AGM) statistical model is proposed since AGM is shown to be more effective compared to the classic Gaussian mixture. The Bayesian learning framework is developed by adopting sampling-based Markov chain Monte Carlo (MCMC) methodology. More precisely, the fundamental learning algorithm is a hybrid Metropolis-Hastings within Gibbs sampling solution which is integrated within a reversible jump MCMC (RJMCMC) learning framework, a self-adapted sampling-based MCMC implementation, that enables model transfer throughout the mixture parameters learning process, therefore, automatically converges to the optimal number of data groups. Furthermore, a feature selection technique is included to tackle the irrelevant and unneeded information from datasets. The performance comparison between AGM and other popular solutions is given and both synthetic and real data sets extracted from challenging applications such as intrusion detection, spam filtering and image categorization are evaluated to show the merits of the proposed approach.
Book Synopsis Contributions to Bayesian Statistical Analysis by : Milovan Krnjajić
Download or read book Contributions to Bayesian Statistical Analysis written by Milovan Krnjajić and published by . This book was released on 2005 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Bayesian Methods for Non-gaussian Data Modeling and Applications by : Tarek Elguebaly
Download or read book Bayesian Methods for Non-gaussian Data Modeling and Applications written by Tarek Elguebaly and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Finite mixture models are among the most useful machine learning techniques and are receiving considerable attention in various applications. The use of finite mixture models in image and signal processing has proved to be of considerable interest in terms of both theoretical development and in their usefulness in several applications. In most of the applications, the Gaussian density is used in the mixture modeling of data. Although a Gaussian mixture may provide a reasonable approximation to many real-world distributions, it is certainly not always the best approximation especially in image and signal processing applications where we often deal with non-Gaussian data. In this thesis, we propose two novel approaches that may be used in modeling non-Gaussian data. These approaches use two highly flexible distributions, the generalized Gaussian distribution (GGD) and the general Beta distribution, in order to model the data. We are motivated by the fact that these distributions are able to fit many distributional shapes and then can be considered as a useful class of flexible models to address several problems and applications involving measurements and features having well-known marked deviation from the Gaussian shape. For the mixture estimation and selection problem, researchers have demonstrated that Bayesian approaches are fully optimal. The Bayesian learning allows the incorporation of prior knowledge in a formal coherent way that avoids overfitting problems. For this reason, we adopt different Bayesian approaches in order to learn our models parameters. First, we present a fully Bayesian approach to analyze finite generalized Gaussian mixture models which incorporate several standard mixtures, such as Laplace and Gaussian. This approach evaluates the posterior distribution and Bayes estimators using a Gibbs sampling algorithm, and selects the number of components in the mixture using the integrated likelihood. We also propose a fully Bayesian approach for finite Beta mixtures learning using a Reversible Jump Markov Chain Monte Carlo (RJMCMC) technique which simultaneously allows cluster assignments, parameters estimation, and the selection of the optimal number of clusters. We then validate the proposed methods by applying them to different image processing applications.
Book Synopsis Nonparametric Bayesian Models for Machine Learning by : Romain Jean Thibaux
Download or read book Nonparametric Bayesian Models for Machine Learning written by Romain Jean Thibaux and published by . This book was released on 2008 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Robust Statistical Modeling Through Nonparametric Bayesian Methods by : Ju Hee Lee
Download or read book Robust Statistical Modeling Through Nonparametric Bayesian Methods written by Ju Hee Lee and published by . This book was released on 2010 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Nonparametric Bayesian models are commonly used to obtain robust statistical inference, and the most popular nonparametric Bayesian model is, arguably, the mixture of Dirichlet processes (MDP) model. In this study, we examine the question of how to obtain more robustness than under a conventional MDP model. In answer to this question, we develop two models from a nonparametric Bayesian viewpoint, and we investigate their properties: (i) the limiting Dirichlet process (limdir) model, and (ii) the local-mass preserving mixture of Dirichlet process (LMDP) model. The limdir model addresses the question of how to perform a ``noninformative" nonparametric Bayesian analysis. Rather than being noninformative, the model requires a slight amount of input, and so provides us with a minimally informative prior distribution with which to conduct a nonparametric Bayesian analysis. The limdir prior distribution can be viewed as the limit of a sequence of mixture of Dirichlet process models. This model requires only modest input, and yet provides posterior behavior which has a number of important qualitative features, including robustness. Second, the LMDP prior distribution focuses on local mass (defined in the paper). To specify such a prior distribution, we carefully consider the behavior of parameters of interest in some small region, and we then select a prior distribution which preserves mass in the region. Local mass preservation ties the mass of the base measure to its dispersion, resulting in robust inference. These two strategies for constructing a prior distribution can be applied to any model based on the Dirichlet process. Calibration of the prior distribution is considered. We use the limdir for the compound decision problem and the one-way analysis of variance problem, and compare its performance to that of mixture of Dirichlet processes models and to parametric Bayesian models on actual data sets. We apply the LMDP model for the one-way analysis of variance problem, and compare its performance to that of a mixture of Dirichlet processes model with a conventional prior structure. In addition to developing the robust nonparametric Bayesian models, the latter part of the study describes a general form of consistency which does not necessarily rely on correct specification of the likelihood. We carefully investigate issues of consistency and inconsistency for a variety of functions of interest, such as equality of subsets of treatment means, without the assumption that the model is correct. We prove that Bayes estimators achieve (asymptotic) consistency under some suitable regularity conditions on the assumed likelihood. More importantly, we find a need to distinguish between the notions of two parameters being "equal to one another" and "close to one another", and we illustrate differences in asymptotic inference for these two statements. This distinction carries with it implications for Bayesian tests of a point null hypothesis.
Book Synopsis A Nonparametric Bayesian Approach to Causal Modelling by : Tim Henry Guimond
Download or read book A Nonparametric Bayesian Approach to Causal Modelling written by Tim Henry Guimond and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Dirichlet process mixture regression (DPMR) method is a technique to produce a very flexible regression model using Bayesian principles based on data clusters. The DPMR method begins by modelling the joint probability density for all variables in a problem. In observational studies, factors which influence treatment assignment (or treatment choice) may also be factors which influence outcomes. In such cases, we refer to these factors as confounders and standard estimates of treatment effects will be biased. Causal modelling approaches allow researchers to make causal inferences from observational data by accounting for confounding variables and thus correcting for the bias in unadjusted models. This thesis develops a fully Bayesian model where the Dirichlet process mixture models the joint distribution of all the variables of interest (confounders, treatment assignment and outcome), and is designed in such a way as to guarantee that this clustering approach adjusts for confounding while also providing a flexible model for outcomes. A local assumption of ignorability is required, as contrasted with the usual global assumption of strong ignorability, and the meaning and consequences of this alternate assumption are explored. The resulting model allows for inferences which are in accordance with causal model principles. In addition to estimating the overall average treatment effect (mean difference between two treatments), it also provides for the determination of conditional outcomes, hence can predict a region of the covariate space where one treatment dominates. Furthermore, the technique's capacity to examine the strongly ignorable assumption is demonstrated. This method can be harnessed to recreate the underlying counterfactual distributions that produce observational data and this is demonstrated with a simulated data set and its results are compared to other common approaches. Finally, the method is applied to a real life data set of an observational study of two possible methods of integrating mental health treatment into the shelter system for homeless men. This analysis of this data demonstrates a situation where treatments have identical outcomes for a subset of the covariate space and a subset of the space where one treatment clearly dominates, thereby informing an individualized patient driven approach to treatment selection.
Book Synopsis Nonparametric Bayesian Models for Unsupervised Learning by : Pu Wang
Download or read book Nonparametric Bayesian Models for Unsupervised Learning written by Pu Wang and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unsupervised learning is an important topic in machine learning. In particular, clustering is an unsupervised learning problem that arises in a variety of applications for data analysis and mining. Unfortunately, clustering is an ill-posed problem and, as such, a challenging one: no ground-truth that can be used to validate clustering results is available. Two issues arise as a consequence. Various clustering algorithms embed their own bias resulting from different optimization criteria. As a result, each algorithm may discover different patterns in a given dataset. The second issue concerns the setting of parameters. In clustering, parameter setting controls the characterization of individual clusters, and the total number of clusters in the data. Clustering ensembles have been proposed to address the issue of different biases induced by various algorithms. Clustering ensembles combine different clustering results, and can provide solutions that are robust against spurious elements in the data. Although clustering ensembles provide a significant advance, they do not address satisfactorily the model selection and the parameter tuning problem. Bayesian approaches have been applied to clustering to address the parameter tuning and model selection issues. Bayesian methods provide a principled way to address these problems by assuming prior distributions on model parameters. Prior distributions assign low probabilities to parameter values which are unlikely. Therefore they serve as regularizers for modeling parameters, and can help avoid over-fitting. In addition, the marginal likelihood is used by Bayesian approaches as the criterion for model selection. Although Bayesian methods provide a principled way to perform parameter tuning and model selection, the key question \How many clusters?" is still open. This is a fundamental question for model selection. A special kind of Bayesian methods, nonparametric Bayesian approaches, have been proposed to address this important model selection issue. Unlike parametric Bayesian models, for which the number of parameters is finite and fixed, nonparametric Bayesian models allow the number of parameters to grow with the number of observations. After observing the data, nonparametric Bayesian models t the data with finite dimensional parameters. An additional issue with clustering is high dimensionality. High-dimensional data pose a difficult challenge to the clustering process. A common scenario with high-dimensional data is that clusters may exist in different subspaces comprised of different combinations of features (dimensions). In other words, data points in a cluster may be similar to each other along a subset of dimensions, but not in all dimensions. People have proposed subspace clustering techniques, a.k.a. co-clustering or bi-clustering, to address the dimensionality issue (here, I use the term co-clustering). Like clustering, also co-clustering suffers from the ill-posed nature and the lack of ground-truth to validate the results. Although attempts have been made in the literature to address individually the major issues related to clustering, no previous work has addressed them jointly. In my dissertation I propose a unified framework that addresses all three issues at the same time. I designed a nonparametric Bayesian clustering ensemble (NBCE) approach, which assumes that multiple observed clustering results are generated from an unknown consensus clustering. The under- lying distribution is assumed to be a mixture distribution with a nonparametric Bayesian prior, i.e., a Dirichlet Process. The number of mixture components, a.k.a. the number of consensus clusters, is learned automatically. By combining the ensemble methodology and nonparametric Bayesian modeling, NBCE addresses both the ill-posed nature and the parameter setting/model selection issues of clustering. Furthermore, NBCE outperforms individual clustering methods, since it can escape local optima by combining multiple clustering results. I also designed a nonparametric Bayesian co-clustering ensemble (NBCCE) technique. NBCCE inherits the advantages of NBCE, and in addition it is effective with high dimensional data. As such, NBCCE provides a unified framework to address all the three aforementioned issues. NBCCE assumes that multiple observed co-clustering results are generated from an unknown consensus co-clustering. The underlying distribution is assumed to be a mixture with a nonparametric Bayesian prior. I developed two models to generate co-clusters in terms of row- and column- clusters. In one case row- and column-clusters are assumed to be independent, and NBCCE assumes two independent Dirichlet Process priors on the hidden consensus co-clustering, one for rows and one for columns. The second model captures the dependence between row- and column-clusters by assuming a Mondrian Process prior on the hidden consensus co-clustering. Combined with Mondrian priors, NBCCE provides more flexibility to fit the data. I have performed extensive evaluation on relational data and protein-molecule interaction data. The empirical evaluation demonstrates the effectiveness of NBCE and NBCCE and their advantages over traditional clustering and co-clustering methods.
Book Synopsis Some Advances in Bayesian Nonparametric Modeling by : Abel Rodriguez
Download or read book Some Advances in Bayesian Nonparametric Modeling written by Abel Rodriguez and published by LAP Lambert Academic Publishing. This book was released on 2009-03 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bayesian nonparametric and semiparametric mixture models have become extremely popular in the last 10 years because they provide flexibility and interpretability while preserving computational simplicity. This book is a contribution to this growing literature, discussing the design of models for collections of distributions and their application to density estimation and nonparametric regression. All methods introduced in this book are discussed in the context of complex scientific applications in public health, epidemiology and finance.
Book Synopsis Nonparametric Bayesian Inference by : Jean-Pierre Florens
Download or read book Nonparametric Bayesian Inference written by Jean-Pierre Florens and published by Springer. This book was released on 2024-07-22 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a compilation of unpublished papers written by Jean-Marie Rolin (with several co-authors) on nonparametric bayesian estimation. Jean-Marie was professor of statistics at University of Louvain and died on November 5th, 2018. He made important contributions in mathematical statistics with applications to different fields like econometrics or biometrics. These papers cover a variety of topics, including: • Mathematical structure of the Bayesian model and main concepts (sufficiency, analarity, invariance...) • Representation of the Dirichlet processes and of the associated Polya urn model and applications to nonparametric bayesian analysis. • Contributions on duration models and on their non parametric bayesian treatment.
