la Almost 12,000 meatpacking and food plant workers have reportedly contracted COVID-19. At least 48 have died. By news.yahoo.com Published On :: Fri, 08 May 2020 12:21:01 -0400 The infections and deaths are spread across roughly two farms and 189 meat and processed food factories. Full Article
la The McMichaels can't be charged with a hate crime by the state in the shooting death of Ahmaud Arbery because the law doesn't exist in Georgia By news.yahoo.com Published On :: Fri, 08 May 2020 17:07:36 -0400 Georgia is one of four states that doesn't have a hate crime law. Arbery's killing has reignited calls for legislation. Full Article
la Joint Modeling of Longitudinal Relational Data and Exogenous Variables By projecteuclid.org Published On :: Thu, 19 Mar 2020 22:02 EDT Rajarshi Guhaniyogi, Abel Rodriguez. Source: Bayesian Analysis, Volume 15, Number 2, 477--503.Abstract: This article proposes a framework based on shared, time varying stochastic latent factor models for modeling relational data in which network and node-attributes co-evolve over time. Our proposed framework is flexible enough to handle both categorical and continuous attributes, allows us to estimate the dimension of the latent social space, and automatically yields Bayesian hypothesis tests for the association between network structure and nodal attributes. Additionally, the model is easy to compute and readily yields inference and prediction for missing link between nodes. We employ our model framework to study co-evolution of international relations between 22 countries and the country specific indicators over a period of 11 years. Full Article
la Bayesian Design of Experiments for Intractable Likelihood Models Using Coupled Auxiliary Models and Multivariate Emulation By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Antony Overstall, James McGree. Source: Bayesian Analysis, Volume 15, Number 1, 103--131.Abstract: A Bayesian design is given by maximising an expected utility over a design space. The utility is chosen to represent the aim of the experiment and its expectation is taken with respect to all unknowns: responses, parameters and/or models. Although straightforward in principle, there are several challenges to finding Bayesian designs in practice. Firstly, the utility and expected utility are rarely available in closed form and require approximation. Secondly, the design space can be of high-dimensionality. In the case of intractable likelihood models, these problems are compounded by the fact that the likelihood function, whose evaluation is required to approximate the expected utility, is not available in closed form. A strategy is proposed to find Bayesian designs for intractable likelihood models. It relies on the development of an automatic, auxiliary modelling approach, using multivariate Gaussian process emulators, to approximate the likelihood function. This is then combined with a copula-based approach to approximate the marginal likelihood (a quantity commonly required to evaluate many utility functions). These approximations are demonstrated on examples of stochastic process models involving experimental aims of both parameter estimation and model comparison. Full Article
la Bayesian Network Marker Selection via the Thresholded Graph Laplacian Gaussian Prior By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Qingpo Cai, Jian Kang, Tianwei Yu. Source: Bayesian Analysis, Volume 15, Number 1, 79--102.Abstract: Selecting informative nodes over large-scale networks becomes increasingly important in many research areas. Most existing methods focus on the local network structure and incur heavy computational costs for the large-scale problem. In this work, we propose a novel prior model for Bayesian network marker selection in the generalized linear model (GLM) framework: the Thresholded Graph Laplacian Gaussian (TGLG) prior, which adopts the graph Laplacian matrix to characterize the conditional dependence between neighboring markers accounting for the global network structure. Under mild conditions, we show the proposed model enjoys the posterior consistency with a diverging number of edges and nodes in the network. We also develop a Metropolis-adjusted Langevin algorithm (MALA) for efficient posterior computation, which is scalable to large-scale networks. We illustrate the superiorities of the proposed method compared with existing alternatives via extensive simulation studies and an analysis of the breast cancer gene expression dataset in the Cancer Genome Atlas (TCGA). Full Article
la The Bayesian Update: Variational Formulations and Gradient Flows By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Nicolas Garcia Trillos, Daniel Sanz-Alonso. Source: Bayesian Analysis, Volume 15, Number 1, 29--56.Abstract: The Bayesian update can be viewed as a variational problem by characterizing the posterior as the minimizer of a functional. The variational viewpoint is far from new and is at the heart of popular methods for posterior approximation. However, some of its consequences seem largely unexplored. We focus on the following one: defining the posterior as the minimizer of a functional gives a natural path towards the posterior by moving in the direction of steepest descent of the functional. This idea is made precise through the theory of gradient flows, allowing to bring new tools to the study of Bayesian models and algorithms. Since the posterior may be characterized as the minimizer of different functionals, several variational formulations may be considered. We study three of them and their three associated gradient flows. We show that, in all cases, the rate of convergence of the flows to the posterior can be bounded by the geodesic convexity of the functional to be minimized. Each gradient flow naturally suggests a nonlinear diffusion with the posterior as invariant distribution. These diffusions may be discretized to build proposals for Markov chain Monte Carlo (MCMC) algorithms. By construction, the diffusions are guaranteed to satisfy a certain optimality condition, and rates of convergence are given by the convexity of the functionals. We use this observation to propose a criterion for the choice of metric in Riemannian MCMC methods. Full Article
la Scalable Bayesian Inference for the Inverse Temperature of a Hidden Potts Model By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Matthew Moores, Geoff Nicholls, Anthony Pettitt, Kerrie Mengersen. Source: Bayesian Analysis, Volume 15, Number 1, 1--27.Abstract: The inverse temperature parameter of the Potts model governs the strength of spatial cohesion and therefore has a major influence over the resulting model fit. A difficulty arises from the dependence of an intractable normalising constant on the value of this parameter and thus there is no closed-form solution for sampling from the posterior distribution directly. There is a variety of computational approaches for sampling from the posterior without evaluating the normalising constant, including the exchange algorithm and approximate Bayesian computation (ABC). A serious drawback of these algorithms is that they do not scale well for models with a large state space, such as images with a million or more pixels. We introduce a parametric surrogate model, which approximates the score function using an integral curve. Our surrogate model incorporates known properties of the likelihood, such as heteroskedasticity and critical temperature. We demonstrate this method using synthetic data as well as remotely-sensed imagery from the Landsat-8 satellite. We achieve up to a hundredfold improvement in the elapsed runtime, compared to the exchange algorithm or ABC. An open-source implementation of our algorithm is available in the R package bayesImageS . Full Article
la Latent Nested Nonparametric Priors (with Discussion) By projecteuclid.org Published On :: Thu, 19 Dec 2019 22:10 EST Federico Camerlenghi, David B. Dunson, Antonio Lijoi, Igor Prünster, Abel Rodríguez. Source: Bayesian Analysis, Volume 14, Number 4, 1303--1356.Abstract: Discrete random structures are important tools in Bayesian nonparametrics and the resulting models have proven effective in density estimation, clustering, topic modeling and prediction, among others. In this paper, we consider nested processes and study the dependence structures they induce. Dependence ranges between homogeneity, corresponding to full exchangeability, and maximum heterogeneity, corresponding to (unconditional) independence across samples. The popular nested Dirichlet process is shown to degenerate to the fully exchangeable case when there are ties across samples at the observed or latent level. To overcome this drawback, inherent to nesting general discrete random measures, we introduce a novel class of latent nested processes. These are obtained by adding common and group-specific completely random measures and, then, normalizing to yield dependent random probability measures. We provide results on the partition distributions induced by latent nested processes, and develop a Markov Chain Monte Carlo sampler for Bayesian inferences. A test for distributional homogeneity across groups is obtained as a by-product. The results and their inferential implications are showcased on synthetic and real data. Full Article
la Estimating the Use of Public Lands: Integrated Modeling of Open Populations with Convolution Likelihood Ecological Abundance Regression By projecteuclid.org Published On :: Thu, 19 Dec 2019 22:10 EST Lutz F. Gruber, Erica F. Stuber, Lyndsie S. Wszola, Joseph J. Fontaine. Source: Bayesian Analysis, Volume 14, Number 4, 1173--1199.Abstract: We present an integrated open population model where the population dynamics are defined by a differential equation, and the related statistical model utilizes a Poisson binomial convolution likelihood. Key advantages of the proposed approach over existing open population models include the flexibility to predict related, but unobserved quantities such as total immigration or emigration over a specified time period, and more computationally efficient posterior simulation by elimination of the need to explicitly simulate latent immigration and emigration. The viability of the proposed method is shown in an in-depth analysis of outdoor recreation participation on public lands, where the surveyed populations changed rapidly and demographic population closure cannot be assumed even within a single day. Full Article
la Implicit Copulas from Bayesian Regularized Regression Smoothers By projecteuclid.org Published On :: Thu, 19 Dec 2019 22:10 EST Nadja Klein, Michael Stanley Smith. Source: Bayesian Analysis, Volume 14, Number 4, 1143--1171.Abstract: We show how to extract the implicit copula of a response vector from a Bayesian regularized regression smoother with Gaussian disturbances. The copula can be used to compare smoothers that employ different shrinkage priors and function bases. We illustrate with three popular choices of shrinkage priors—a pairwise prior, the horseshoe prior and a g prior augmented with a point mass as employed for Bayesian variable selection—and both univariate and multivariate function bases. The implicit copulas are high-dimensional, have flexible dependence structures that are far from that of a Gaussian copula, and are unavailable in closed form. However, we show how they can be evaluated by first constructing a Gaussian copula conditional on the regularization parameters, and then integrating over these. Combined with non-parametric margins the regularized smoothers can be used to model the distribution of non-Gaussian univariate responses conditional on the covariates. Efficient Markov chain Monte Carlo schemes for evaluating the copula are given for this case. Using both simulated and real data, we show how such copula smoothing models can improve the quality of resulting function estimates and predictive distributions. Full Article
la Extrinsic Gaussian Processes for Regression and Classification on Manifolds By projecteuclid.org Published On :: Tue, 11 Jun 2019 04:00 EDT Lizhen Lin, Niu Mu, Pokman Cheung, David Dunson. Source: Bayesian Analysis, Volume 14, Number 3, 907--926.Abstract: Gaussian processes (GPs) are very widely used for modeling of unknown functions or surfaces in applications ranging from regression to classification to spatial processes. Although there is an increasingly vast literature on applications, methods, theory and algorithms related to GPs, the overwhelming majority of this literature focuses on the case in which the input domain corresponds to a Euclidean space. However, particularly in recent years with the increasing collection of complex data, it is commonly the case that the input domain does not have such a simple form. For example, it is common for the inputs to be restricted to a non-Euclidean manifold, a case which forms the motivation for this article. In particular, we propose a general extrinsic framework for GP modeling on manifolds, which relies on embedding of the manifold into a Euclidean space and then constructing extrinsic kernels for GPs on their images. These extrinsic Gaussian processes (eGPs) are used as prior distributions for unknown functions in Bayesian inferences. Our approach is simple and general, and we show that the eGPs inherit fine theoretical properties from GP models in Euclidean spaces. We consider applications of our models to regression and classification problems with predictors lying in a large class of manifolds, including spheres, planar shape spaces, a space of positive definite matrices, and Grassmannians. Our models can be readily used by practitioners in biological sciences for various regression and classification problems, such as disease diagnosis or detection. Our work is also likely to have impact in spatial statistics when spatial locations are on the sphere or other geometric spaces. Full Article
la Jointly Robust Prior for Gaussian Stochastic Process in Emulation, Calibration and Variable Selection By projecteuclid.org Published On :: Tue, 11 Jun 2019 04:00 EDT Mengyang Gu. Source: Bayesian Analysis, Volume 14, Number 3, 877--905.Abstract: Gaussian stochastic process (GaSP) has been widely used in two fundamental problems in uncertainty quantification, namely the emulation and calibration of mathematical models. Some objective priors, such as the reference prior, are studied in the context of emulating (approximating) computationally expensive mathematical models. In this work, we introduce a new class of priors, called the jointly robust prior, for both the emulation and calibration. This prior is designed to maintain various advantages from the reference prior. In emulation, the jointly robust prior has an appropriate tail decay rate as the reference prior, and is computationally simpler than the reference prior in parameter estimation. Moreover, the marginal posterior mode estimation with the jointly robust prior can separate the influential and inert inputs in mathematical models, while the reference prior does not have this property. We establish the posterior propriety for a large class of priors in calibration, including the reference prior and jointly robust prior in general scenarios, but the jointly robust prior is preferred because the calibrated mathematical model typically predicts the reality well. The jointly robust prior is used as the default prior in two new R packages, called “RobustGaSP” and “RobustCalibration”, available on CRAN for emulation and calibration, respectively. Full Article
la Bayesian Zero-Inflated Negative Binomial Regression Based on Pólya-Gamma Mixtures By projecteuclid.org Published On :: Tue, 11 Jun 2019 04:00 EDT Brian Neelon. Source: Bayesian Analysis, Volume 14, Number 3, 849--875.Abstract: Motivated by a study examining spatiotemporal patterns in inpatient hospitalizations, we propose an efficient Bayesian approach for fitting zero-inflated negative binomial models. To facilitate posterior sampling, we introduce a set of latent variables that are represented as scale mixtures of normals, where the precision terms follow independent Pólya-Gamma distributions. Conditional on the latent variables, inference proceeds via straightforward Gibbs sampling. For fixed-effects models, our approach is comparable to existing methods. However, our model can accommodate more complex data structures, including multivariate and spatiotemporal data, settings in which current approaches often fail due to computational challenges. Using simulation studies, we highlight key features of the method and compare its performance to other estimation procedures. We apply the approach to a spatiotemporal analysis examining the number of annual inpatient admissions among United States veterans with type 2 diabetes. Full Article
la High-Dimensional Confounding Adjustment Using Continuous Spike and Slab Priors By projecteuclid.org Published On :: Tue, 11 Jun 2019 04:00 EDT Joseph Antonelli, Giovanni Parmigiani, Francesca Dominici. Source: Bayesian Analysis, Volume 14, Number 3, 825--848.Abstract: In observational studies, estimation of a causal effect of a treatment on an outcome relies on proper adjustment for confounding. If the number of the potential confounders ( $p$ ) is larger than the number of observations ( $n$ ), then direct control for all potential confounders is infeasible. Existing approaches for dimension reduction and penalization are generally aimed at predicting the outcome, and are less suited for estimation of causal effects. Under standard penalization approaches (e.g. Lasso), if a variable $X_{j}$ is strongly associated with the treatment $T$ but weakly with the outcome $Y$ , the coefficient $eta_{j}$ will be shrunk towards zero thus leading to confounding bias. Under the assumption of a linear model for the outcome and sparsity, we propose continuous spike and slab priors on the regression coefficients $eta_{j}$ corresponding to the potential confounders $X_{j}$ . Specifically, we introduce a prior distribution that does not heavily shrink to zero the coefficients ( $eta_{j}$ s) of the $X_{j}$ s that are strongly associated with $T$ but weakly associated with $Y$ . We compare our proposed approach to several state of the art methods proposed in the literature. Our proposed approach has the following features: 1) it reduces confounding bias in high dimensional settings; 2) it shrinks towards zero coefficients of instrumental variables; and 3) it achieves good coverages even in small sample sizes. We apply our approach to the National Health and Nutrition Examination Survey (NHANES) data to estimate the causal effects of persistent pesticide exposure on triglyceride levels. Full Article
la Model Criticism in Latent Space By projecteuclid.org Published On :: Tue, 11 Jun 2019 04:00 EDT Sohan Seth, Iain Murray, Christopher K. I. Williams. Source: Bayesian Analysis, Volume 14, Number 3, 703--725.Abstract: Model criticism is usually carried out by assessing if replicated data generated under the fitted model looks similar to the observed data, see e.g. Gelman, Carlin, Stern, and Rubin (2004, p. 165). This paper presents a method for latent variable models by pulling back the data into the space of latent variables, and carrying out model criticism in that space. Making use of a model's structure enables a more direct assessment of the assumptions made in the prior and likelihood. We demonstrate the method with examples of model criticism in latent space applied to factor analysis, linear dynamical systems and Gaussian processes. Full Article
la Alleviating Spatial Confounding for Areal Data Problems by Displacing the Geographical Centroids By projecteuclid.org Published On :: Fri, 31 May 2019 22:05 EDT Marcos Oliveira Prates, Renato Martins Assunção, Erica Castilho Rodrigues. Source: Bayesian Analysis, Volume 14, Number 2, 623--647.Abstract: Spatial confounding between the spatial random effects and fixed effects covariates has been recently discovered and showed that it may bring misleading interpretation to the model results. Techniques to alleviate this problem are based on decomposing the spatial random effect and fitting a restricted spatial regression. In this paper, we propose a different approach: a transformation of the geographic space to ensure that the unobserved spatial random effect added to the regression is orthogonal to the fixed effects covariates. Our approach, named SPOCK, has the additional benefit of providing a fast and simple computational method to estimate the parameters. Also, it does not constrain the distribution class assumed for the spatial error term. A simulation study and real data analyses are presented to better understand the advantages of the new method in comparison with the existing ones. Full Article
la Bayes Factor Testing of Multiple Intraclass Correlations By projecteuclid.org Published On :: Wed, 13 Mar 2019 22:00 EDT Joris Mulder, Jean-Paul Fox. Source: Bayesian Analysis, Volume 14, Number 2, 521--552.Abstract: The intraclass correlation plays a central role in modeling hierarchically structured data, such as educational data, panel data, or group-randomized trial data. It represents relevant information concerning the between-group and within-group variation. Methods for Bayesian hypothesis tests concerning the intraclass correlation are proposed to improve decision making in hierarchical data analysis and to assess the grouping effect across different group categories. Estimation and testing methods for the intraclass correlation coefficient are proposed under a marginal modeling framework where the random effects are integrated out. A class of stretched beta priors is proposed on the intraclass correlations, which is equivalent to shifted $F$ priors for the between groups variances. Through a parameter expansion it is shown that this prior is conditionally conjugate under the marginal model yielding efficient posterior computation. A special improper case results in accurate coverage rates of the credible intervals even for minimal sample size and when the true intraclass correlation equals zero. Bayes factor tests are proposed for testing multiple precise and order hypotheses on intraclass correlations. These tests can be used when prior information about the intraclass correlations is available or absent. For the noninformative case, a generalized fractional Bayes approach is developed. The method enables testing the presence and strength of grouped data structures without introducing random effects. The methodology is applied to a large-scale survey study on international mathematics achievement at fourth grade to test the heterogeneity in the clustering of students in schools across countries and assessment cycles. Full Article
la Efficient Bayesian Regularization for Graphical Model Selection By projecteuclid.org Published On :: Wed, 13 Mar 2019 22:00 EDT Suprateek Kundu, Bani K. Mallick, Veera Baladandayuthapani. Source: Bayesian Analysis, Volume 14, Number 2, 449--476.Abstract: There has been an intense development in the Bayesian graphical model literature over the past decade; however, most of the existing methods are restricted to moderate dimensions. We propose a novel graphical model selection approach for large dimensional settings where the dimension increases with the sample size, by decoupling model fitting and covariance selection. First, a full model based on a complete graph is fit under a novel class of mixtures of inverse–Wishart priors, which induce shrinkage on the precision matrix under an equivalence with Cholesky-based regularization, while enabling conjugate updates. Subsequently, a post-fitting model selection step uses penalized joint credible regions to perform model selection. This allows our methods to be computationally feasible for large dimensional settings using a combination of straightforward Gibbs samplers and efficient post-fitting inferences. Theoretical guarantees in terms of selection consistency are also established. Simulations show that the proposed approach compares favorably with competing methods, both in terms of accuracy metrics and computation times. We apply this approach to a cancer genomics data example. Full Article
la Variational Message Passing for Elaborate Response Regression Models By projecteuclid.org Published On :: Wed, 13 Mar 2019 22:00 EDT M. W. McLean, M. P. Wand. Source: Bayesian Analysis, Volume 14, Number 2, 371--398.Abstract: We build on recent work concerning message passing approaches to approximate fitting and inference for arbitrarily large regression models. The focus is on regression models where the response variable is modeled to have an elaborate distribution, which is loosely defined to mean a distribution that is more complicated than common distributions such as those in the Bernoulli, Poisson and Normal families. Examples of elaborate response families considered here are the Negative Binomial and $t$ families. Variational message passing is more challenging due to some of the conjugate exponential families being non-standard and numerical integration being needed. Nevertheless, a factor graph fragment approach means the requisite calculations only need to be done once for a particular elaborate response distribution family. Computer code can be compartmentalized, including that involving numerical integration. A major finding of this work is that the modularity of variational message passing extends to elaborate response regression models. Full Article
la Modeling Population Structure Under Hierarchical Dirichlet Processes By projecteuclid.org Published On :: Wed, 13 Mar 2019 22:00 EDT Lloyd T. Elliott, Maria De Iorio, Stefano Favaro, Kaustubh Adhikari, Yee Whye Teh. Source: Bayesian Analysis, Volume 14, Number 2, 313--339.Abstract: We propose a Bayesian nonparametric model to infer population admixture, extending the hierarchical Dirichlet process to allow for correlation between loci due to linkage disequilibrium. Given multilocus genotype data from a sample of individuals, the proposed model allows inferring and classifying individuals as unadmixed or admixed, inferring the number of subpopulations ancestral to an admixed population and the population of origin of chromosomal regions. Our model does not assume any specific mutation process, and can be applied to most of the commonly used genetic markers. We present a Markov chain Monte Carlo (MCMC) algorithm to perform posterior inference from the model and we discuss some methods to summarize the MCMC output for the analysis of population admixture. Finally, we demonstrate the performance of the proposed model in a real application, using genetic data from the ectodysplasin-A receptor (EDAR) gene, which is considered to be ancestry-informative due to well-known variations in allele frequency as well as phenotypic effects across ancestry. The structure analysis of this dataset leads to the identification of a rare haplotype in Europeans. We also conduct a simulated experiment and show that our algorithm outperforms parametric methods. Full Article
la Separable covariance arrays via the Tucker product, with applications to multivariate relational data By projecteuclid.org Published On :: Wed, 13 Jun 2012 14:27 EDT Peter D. HoffSource: Bayesian Anal., Volume 6, Number 2, 179--196.Abstract: Modern datasets are often in the form of matrices or arrays, potentially having correlations along each set of data indices. For example, data involving repeated measurements of several variables over time may exhibit temporal correlation as well as correlation among the variables. A possible model for matrix-valued data is the class of matrix normal distributions, which is parametrized by two covariance matrices, one for each index set of the data. In this article we discuss an extension of the matrix normal model to accommodate multidimensional data arrays, or tensors. We show how a particular array-matrix product can be used to generate the class of array normal distributions having separable covariance structure. We derive some properties of these covariance structures and the corresponding array normal distributions, and show how the array-matrix product can be used to define a semi-conjugate prior distribution and calculate the corresponding posterior distribution. We illustrate the methodology in an analysis of multivariate longitudinal network data which take the form of a four-way array. Full Article
la Larry Brown’s Work on Admissibility By projecteuclid.org Published On :: Wed, 08 Jan 2020 04:00 EST Iain M. Johnstone. Source: Statistical Science, Volume 34, Number 4, 657--668.Abstract: Many papers in the early part of Brown’s career focused on the admissibility or otherwise of estimators of a vector parameter. He established that inadmissibility of invariant estimators in three and higher dimensions is a general phenomenon, and found deep and beautiful connections between admissibility and other areas of mathematics. This review touches on several of his major contributions, with a focus on his celebrated 1971 paper connecting admissibility, recurrence and elliptic partial differential equations. Full Article
la Larry Brown’s Contributions to Parametric Inference, Decision Theory and Foundations: A Survey By projecteuclid.org Published On :: Wed, 08 Jan 2020 04:00 EST James O. Berger, Anirban DasGupta. Source: Statistical Science, Volume 34, Number 4, 621--634.Abstract: This article gives a panoramic survey of the general area of parametric statistical inference, decision theory and foundations of statistics for the period 1965–2010 through the lens of Larry Brown’s contributions to varied aspects of this massive area. The article goes over sufficiency, shrinkage estimation, admissibility, minimaxity, complete class theorems, estimated confidence, conditional confidence procedures, Edgeworth and higher order asymptotic expansions, variational Bayes, Stein’s SURE, differential inequalities, geometrization of convergence rates, asymptotic equivalence, aspects of empirical process theory, inference after model selection, unified frequentist and Bayesian testing, and Wald’s sequential theory. A reasonably comprehensive bibliography is provided. Full Article
la The Geometry of Continuous Latent Space Models for Network Data By projecteuclid.org Published On :: Fri, 11 Oct 2019 04:03 EDT Anna L. Smith, Dena M. Asta, Catherine A. Calder. Source: Statistical Science, Volume 34, Number 3, 428--453.Abstract: We review the class of continuous latent space (statistical) models for network data, paying particular attention to the role of the geometry of the latent space. In these models, the presence/absence of network dyadic ties are assumed to be conditionally independent given the dyads’ unobserved positions in a latent space. In this way, these models provide a probabilistic framework for embedding network nodes in a continuous space equipped with a geometry that facilitates the description of dependence between random dyadic ties. Specifically, these models naturally capture homophilous tendencies and triadic clustering, among other common properties of observed networks. In addition to reviewing the literature on continuous latent space models from a geometric perspective, we highlight the important role the geometry of the latent space plays on properties of networks arising from these models via intuition and simulation. Finally, we discuss results from spectral graph theory that allow us to explore the role of the geometry of the latent space, independent of network size. We conclude with conjectures about how these results might be used to infer the appropriate latent space geometry from observed networks. Full Article
la Lasso Meets Horseshoe: A Survey By projecteuclid.org Published On :: Fri, 11 Oct 2019 04:03 EDT Anindya Bhadra, Jyotishka Datta, Nicholas G. Polson, Brandon Willard. Source: Statistical Science, Volume 34, Number 3, 405--427.Abstract: The goal of this paper is to contrast and survey the major advances in two of the most commonly used high-dimensional techniques, namely, the Lasso and horseshoe regularization. Lasso is a gold standard for predictor selection while horseshoe is a state-of-the-art Bayesian estimator for sparse signals. Lasso is fast and scalable and uses convex optimization whilst the horseshoe is nonconvex. Our novel perspective focuses on three aspects: (i) theoretical optimality in high-dimensional inference for the Gaussian sparse model and beyond, (ii) efficiency and scalability of computation and (iii) methodological development and performance. Full Article
la ROS Regression: Integrating Regularization with Optimal Scaling Regression By projecteuclid.org Published On :: Fri, 11 Oct 2019 04:03 EDT Jacqueline J. Meulman, Anita J. van der Kooij, Kevin L. W. Duisters. Source: Statistical Science, Volume 34, Number 3, 361--390.Abstract: We present a methodology for multiple regression analysis that deals with categorical variables (possibly mixed with continuous ones), in combination with regularization, variable selection and high-dimensional data ($Pgg N$). Regularization and optimal scaling (OS) are two important extensions of ordinary least squares regression (OLS) that will be combined in this paper. There are two data analytic situations for which optimal scaling was developed. One is the analysis of categorical data, and the other the need for transformations because of nonlinear relationships between predictors and outcome. Optimal scaling of categorical data finds quantifications for the categories, both for the predictors and for the outcome variables, that are optimal for the regression model in the sense that they maximize the multiple correlation. When nonlinear relationships exist, nonlinear transformation of predictors and outcome maximize the multiple correlation in the same way. We will consider a variety of transformation types; typically we use step functions for categorical variables, and smooth (spline) functions for continuous variables. Both types of functions can be restricted to be monotonic, preserving the ordinal information in the data. In combination with optimal scaling, three popular regularization methods will be considered: Ridge regression, the Lasso and the Elastic Net. The resulting method will be called ROS Regression (Regularized Optimal Scaling Regression). The OS algorithm provides straightforward and efficient estimation of the regularized regression coefficients, automatically gives the Group Lasso and Blockwise Sparse Regression, and extends them by the possibility to maintain ordinal properties in the data. Extended examples are provided. Full Article
la Statistical Analysis of Zero-Inflated Nonnegative Continuous Data: A Review By projecteuclid.org Published On :: Thu, 18 Jul 2019 22:01 EDT Lei Liu, Ya-Chen Tina Shih, Robert L. Strawderman, Daowen Zhang, Bankole A. Johnson, Haitao Chai. Source: Statistical Science, Volume 34, Number 2, 253--279.Abstract: Zero-inflated nonnegative continuous (or semicontinuous) data arise frequently in biomedical, economical, and ecological studies. Examples include substance abuse, medical costs, medical care utilization, biomarkers (e.g., CD4 cell counts, coronary artery calcium scores), single cell gene expression rates, and (relative) abundance of microbiome. Such data are often characterized by the presence of a large portion of zero values and positive continuous values that are skewed to the right and heteroscedastic. Both of these features suggest that no simple parametric distribution may be suitable for modeling such type of outcomes. In this paper, we review statistical methods for analyzing zero-inflated nonnegative outcome data. We will start with the cross-sectional setting, discussing ways to separate zero and positive values and introducing flexible models to characterize right skewness and heteroscedasticity in the positive values. We will then present models of correlated zero-inflated nonnegative continuous data, using random effects to tackle the correlation on repeated measures from the same subject and that across different parts of the model. We will also discuss expansion to related topics, for example, zero-inflated count and survival data, nonlinear covariate effects, and joint models of longitudinal zero-inflated nonnegative continuous data and survival. Finally, we will present applications to three real datasets (i.e., microbiome, medical costs, and alcohol drinking) to illustrate these methods. Example code will be provided to facilitate applications of these methods. Full Article
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la Blake Lively's Favorite Affordable Jeans Brand Is Having a Major Sale Right Now By www.health.com Published On :: Mon, 25 Nov 2019 16:40:00 -0500 Here's everything you need to know about Old Navy's Black Friday and Cyber Monday plans. Full Article
la Taylor Swift, Hailey Bieber, and Tons of Other Celebs’ Favorite Leggings Are on Sale Ahead of Black Friday By www.health.com Published On :: Wed, 27 Nov 2019 14:16:17 -0500 Here’s where you can snag their Alo Yoga Moto leggings for less. Full Article
la Gabrielle Union's Mesmerizing Tie Dye Activewear Set Is On Sale for Black Friday By www.health.com Published On :: Wed, 27 Nov 2019 15:35:02 -0500 The rainbow sports bra and leggings set from Splits59 is a must-have for anyone craving a pop of color in their workout wardrobe. Full Article
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la Nike Launches Zoom Pulse Sneakers for Medical Workers Who Are On Their Feet All Day By www.health.com Published On :: Fri, 13 Dec 2019 13:45:17 -0500 The new style is available to shop today. Full Article
la Amazon Just Launched an Exclusive Clothing Collection Full of Warm and Comfy Basics Under $45 By www.health.com Published On :: Tue, 17 Dec 2019 12:23:05 -0500 The womenswear line is new, and there’s already a variety of items to shop. Full Article
la Shoppers Swear These $30 Colorfulkoala Leggings Are the Ultimate Lululemon Dupes By www.health.com Published On :: Wed, 11 Dec 2019 12:44:27 -0500 And they’re available in 19 fun prints. Full Article
la Allometric Analysis Detects Brain Size-Independent Effects of Sex and Sex Chromosome Complement on Human Cerebellar Organization By www.jneurosci.org Published On :: 2017-05-24 Catherine MankiwMay 24, 2017; 37:5221-5231Development Plasticity Repair Full Article
la The Cognitive Thalamus as a Gateway to Mental Representations By www.jneurosci.org Published On :: 2019-01-02 Mathieu WolffJan 2, 2019; 39:3-14Viewpoints Full Article
la Afferents and Homotypic Neighbors Regulate Horizontal Cell Morphology, Connectivity, and Retinal Coverage By www.jneurosci.org Published On :: 2005-03-02 Benjamin E. ReeseMar 2, 2005; 25:2167-2175BehavioralSystemsCognitive Full Article
la Astrocytes Modulate Baroreflex Sensitivity at the Level of the Nucleus of the Solitary Tract By www.jneurosci.org Published On :: 2020-04-08 Svetlana MastitskayaApr 8, 2020; 40:3052-3062Systems/Circuits Full Article
la Dural Calcitonin Gene-Related Peptide Produces Female-Specific Responses in Rodent Migraine Models By www.jneurosci.org Published On :: 2019-05-29 Amanda AvonaMay 29, 2019; 39:4323-4331Systems/Circuits Full Article