ea ACT and Teachers’ Union Partner to Provide Remote Learning Resources Amid Pandemic By marketbrief.edweek.org Published On :: Wed, 06 May 2020 20:18:13 +0000 ACT and the American Federation of Teachers are partnering to provide free resources as educators increasingly switch to distance learning amid the COVID-19 pandemic. The post ACT and Teachers’ Union Partner to Provide Remote Learning Resources Amid Pandemic appeared first on Market Brief. Full Article Marketplace K-12 Assessment / Testing Business Strategy Career / College Readiness Coronavirus COVID-19 Curriculum / Digital Curriculum Online / Virtual Learning
ea Pearson K12 Spinoff Rebranded as ‘Savvas Learning Company’ By marketbrief.edweek.org Published On :: Wed, 06 May 2020 21:20:35 +0000 Savvas Learning Company will continue to provide its K-12 products and services, and is working to support districts with their remote learning needs during school closures. The post Pearson K12 Spinoff Rebranded as ‘Savvas Learning Company’ appeared first on Market Brief. Full Article Marketplace K-12 Business Strategy Data Mergers and Acquisitions Online / Virtual Learning
ea 4 Ways to Help Students Cultivate Meaningful Connections Through Tech By marketbrief.edweek.org Published On :: Thu, 07 May 2020 15:19:55 +0000 The CEO of Move This World isn't big on screen time, but in the midst of the coronavirus pandemic, technology--when used with care--can help strengthen relationships. The post 4 Ways to Help Students Cultivate Meaningful Connections Through Tech appeared first on Market Brief. Full Article Marketplace K-12 Coronavirus COVID-19 Educational Technology/Ed-Tech Online / Virtual Learning Social Emotional Learning (SEL) wellbeing
ea Item 01: Ellis Ashmead-Bartlett diary, 1915-1917 By feedproxy.google.com Published On :: 10/07/2015 12:00:00 AM Full Article
ea Item 01: Ellis Ashmead-Bartlett diary, 1915-1917 By feedproxy.google.com Published On :: 10/07/2015 12:00:00 AM Full Article
ea Smart research for HSC students: Better searching with online resources By feedproxy.google.com Published On :: Mon, 04 May 2020 01:20:48 +0000 In this online session, we simplify searching for you so that the skills you need in one resource will work wherever you are. Full Article
ea Smart research for HSC students: Citing your work and avoiding plagiarism By feedproxy.google.com Published On :: Mon, 04 May 2020 01:33:47 +0000 This session brings together the key resources for HSC subjects, including those that are useful for studying Advanced and Extension courses. Full Article
ea Smart research for HSC students: Essential Library resources for your research and study By feedproxy.google.com Published On :: Mon, 04 May 2020 01:47:45 +0000 This session brings together the key resources for HSC subjects, including those that are useful for studying Advanced and Extension courses. Full Article
ea Russia probe transcripts released by House Intelligence Committee By news.yahoo.com Published On :: Thu, 07 May 2020 23:20:04 -0400 Reaction and analysis from Fox News contributor Byron York and former Florida Attorney General Pam Bondi. Full Article
ea Federal watchdog finds 'reasonable grounds to believe' vaccine doctor's ouster was retaliation, lawyers say By news.yahoo.com Published On :: Fri, 08 May 2020 16:37:13 -0400 The Office of Special Counsel is recommending that ousted vaccine official Dr. Rick Bright be reinstated while it investigates his case, his lawyers announced Friday.Bright while leading coronavirus vaccine development was recently removed from his position as the director of the Department of Health and Human Services' Biomedical Advanced Research and Development Authority, and he alleges it was because he insisted congressional funding not go toward "drugs, vaccines, and other technologies that lack scientific merit" and limited the "broad use" of hydroxychloroquine after it was touted by President Trump. In a whistleblower complaint, he alleged "cronyism" at HHS. He has also alleged he was "pressured to ignore or dismiss expert scientific recommendations and instead to award lucrative contracts based on political connections."On Friday, Bright's lawyers said that the Office of Special Counsel has determined there are "reasonable grounds to believe" his firing was retaliation, The New York Times reports. The federal watchdog also recommended he be reinstated for 45 days to give the office "sufficient time to complete its investigation of Bright's allegations," CNN reports. The decision on whether to do so falls on Secretary of Health and Human Services Alex Azar, and Office of Special Counsel recommendations are "not binding," the Times notes. More stories from theweek.com Outed CIA agent Valerie Plame is running for Congress, and her launch video looks like a spy movie trailer 7 scathing cartoons about America's rush to reopen Trump says he couldn't have exposed WWII vets to COVID-19 because the wind was blowing the wrong way Full Article
ea Boeing says it's about to start building the 737 Max plane again in the middle of the coronavirus pandemic, even though it already has more planes than it can deliver By news.yahoo.com Published On :: Fri, 08 May 2020 12:44:06 -0400 Boeing CEO Dave Calhoun said the company was aiming to resume production this month, despite the ongoing grounding and coronavirus pandemic. Full Article
ea Delta, citing health concerns, drops service to 10 US airports. Is yours on the list? By news.yahoo.com Published On :: Fri, 08 May 2020 18:41:45 -0400 Delta said it is making the move to protect employees amid the coronavirus pandemic, but planes have been flying near empty Full Article
ea Chaffetz: I don't understand why Adam Schiff continues to have a security clearance By news.yahoo.com Published On :: Fri, 08 May 2020 14:43:30 -0400 Fox News contributor Jason Chaffetz and Andy McCarthy react to House Intelligence transcripts on Russia probe. Full Article
ea Coronavirus deals 'powerful blow' to Putin's grand plans By news.yahoo.com Published On :: Thu, 07 May 2020 22:09:16 -0400 The bombastic military parade through Moscow's Red Square on Saturday was slated to be the spectacle of the year on the Kremlin's calendar. Standing with Chinese leader Xi Jinping and French President Emmanuel Macron, President Vladimir Putin would have overseen a 90-minute procession of Russia's military might, showcasing 15,000 troops and the latest hardware. Now, military jets will roar over an eerily quiet Moscow, spurting red, white and blue smoke to mark 75 years since the defeat of Nazi Germany. Full Article
ea ‘Selfish, tribal and divided’: Barack Obama warns of changes to American way of life in leaked audio slamming Trump administration By news.yahoo.com Published On :: Sat, 09 May 2020 07:22:00 -0400 Barack Obama said the “rule of law is at risk” following the justice department’s decision to drop charges against former Trump advisor Mike Flynn, as he issued a stark warning about the long-term impact on the American way of life by his successor. Full Article
ea New Zealand says it backs Taiwan's role in WHO due to success with coronavirus By news.yahoo.com Published On :: Thu, 07 May 2020 23:20:43 -0400 Full Article
ea 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
ea Meet the Ohio health expert who has a fan club — and Republicans trying to stop her By news.yahoo.com Published On :: Sat, 09 May 2020 05:04:00 -0400 Some Buckeyes are not comfortable being told by a "woman in power" to quarantine, one expert said. Full Article
ea 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
ea Nearly one-third of Americans believe a coronavirus vaccine exists and is being withheld, survey finds By news.yahoo.com Published On :: Fri, 08 May 2020 16:49:35 -0400 The Democracy Fund + UCLA Nationscape Project found some misinformation about the coronavirus is more widespread that you might think. Full Article
ea Coronavirus: Chinese official admits health system weaknesses By news.yahoo.com Published On :: Sat, 09 May 2020 11:02:40 -0400 China says it will improve public health systems after criticism of its early response to the virus. Full Article
ea A Loss-Based Prior for Variable Selection in Linear Regression Methods By projecteuclid.org Published On :: Thu, 19 Mar 2020 22:02 EDT Cristiano Villa, Jeong Eun Lee. Source: Bayesian Analysis, Volume 15, Number 2, 533--558.Abstract: In this work we propose a novel model prior for variable selection in linear regression. The idea is to determine the prior mass by considering the worth of each of the regression models, given the number of possible covariates under consideration. The worth of a model consists of the information loss and the loss due to model complexity. While the information loss is determined objectively, the loss expression due to model complexity is flexible and, the penalty on model size can be even customized to include some prior knowledge. Some versions of the loss-based prior are proposed and compared empirically. Through simulation studies and real data analyses, we compare the proposed prior to the Scott and Berger prior, for noninformative scenarios, and with the Beta-Binomial prior, for informative scenarios. Full Article
ea A New Bayesian Approach to Robustness Against Outliers in Linear Regression By projecteuclid.org Published On :: Thu, 19 Mar 2020 22:02 EDT Philippe Gagnon, Alain Desgagné, Mylène Bédard. Source: Bayesian Analysis, Volume 15, Number 2, 389--414.Abstract: Linear regression is ubiquitous in statistical analysis. It is well understood that conflicting sources of information may contaminate the inference when the classical normality of errors is assumed. The contamination caused by the light normal tails follows from an undesirable effect: the posterior concentrates in an area in between the different sources with a large enough scaling to incorporate them all. The theory of conflict resolution in Bayesian statistics (O’Hagan and Pericchi (2012)) recommends to address this problem by limiting the impact of outliers to obtain conclusions consistent with the bulk of the data. In this paper, we propose a model with super heavy-tailed errors to achieve this. We prove that it is wholly robust, meaning that the impact of outliers gradually vanishes as they move further and further away from the general trend. The super heavy-tailed density is similar to the normal outside of the tails, which gives rise to an efficient estimation procedure. In addition, estimates are easily computed. This is highlighted via a detailed user guide, where all steps are explained through a simulated case study. The performance is shown using simulation. All required code is given. Full Article
ea Dynamic Quantile Linear Models: A Bayesian Approach By projecteuclid.org Published On :: Thu, 19 Mar 2020 22:02 EDT Kelly C. M. Gonçalves, Hélio S. Migon, Leonardo S. Bastos. Source: Bayesian Analysis, Volume 15, Number 2, 335--362.Abstract: The paper introduces a new class of models, named dynamic quantile linear models, which combines dynamic linear models with distribution-free quantile regression producing a robust statistical method. Bayesian estimation for the dynamic quantile linear model is performed using an efficient Markov chain Monte Carlo algorithm. The paper also proposes a fast sequential procedure suited for high-dimensional predictive modeling with massive data, where the generating process is changing over time. The proposed model is evaluated using synthetic and well-known time series data. The model is also applied to predict annual incidence of tuberculosis in the state of Rio de Janeiro and compared with global targets set by the World Health Organization. Full Article
ea Learning Semiparametric Regression with Missing Covariates Using Gaussian Process Models By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Abhishek Bishoyi, Xiaojing Wang, Dipak K. Dey. Source: Bayesian Analysis, Volume 15, Number 1, 215--239.Abstract: Missing data often appear as a practical problem while applying classical models in the statistical analysis. In this paper, we consider a semiparametric regression model in the presence of missing covariates for nonparametric components under a Bayesian framework. As it is known that Gaussian processes are a popular tool in nonparametric regression because of their flexibility and the fact that much of the ensuing computation is parametric Gaussian computation. However, in the absence of covariates, the most frequently used covariance functions of a Gaussian process will not be well defined. We propose an imputation method to solve this issue and perform our analysis using Bayesian inference, where we specify the objective priors on the parameters of Gaussian process models. Several simulations are conducted to illustrate effectiveness of our proposed method and further, our method is exemplified via two real datasets, one through Langmuir equation, commonly used in pharmacokinetic models, and another through Auto-mpg data taken from the StatLib library. Full Article
ea Adaptive Bayesian Nonparametric Regression Using a Kernel Mixture of Polynomials with Application to Partial Linear Models By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Fangzheng Xie, Yanxun Xu. Source: Bayesian Analysis, Volume 15, Number 1, 159--186.Abstract: We propose a kernel mixture of polynomials prior for Bayesian nonparametric regression. The regression function is modeled by local averages of polynomials with kernel mixture weights. We obtain the minimax-optimal contraction rate of the full posterior distribution up to a logarithmic factor by estimating metric entropies of certain function classes. Under the assumption that the degree of the polynomials is larger than the unknown smoothness level of the true function, the posterior contraction behavior can adapt to this smoothness level provided an upper bound is known. We also provide a frequentist sieve maximum likelihood estimator with a near-optimal convergence rate. We further investigate the application of the kernel mixture of polynomials to partial linear models and obtain both the near-optimal rate of contraction for the nonparametric component and the Bernstein-von Mises limit (i.e., asymptotic normality) of the parametric component. The proposed method is illustrated with numerical examples and shows superior performance in terms of computational efficiency, accuracy, and uncertainty quantification compared to the local polynomial regression, DiceKriging, and the robust Gaussian stochastic process. Full Article
ea Hierarchical Normalized Completely Random Measures for Robust Graphical Modeling By projecteuclid.org Published On :: Thu, 19 Dec 2019 22:10 EST Andrea Cremaschi, Raffaele Argiento, Katherine Shoemaker, Christine Peterson, Marina Vannucci. Source: Bayesian Analysis, Volume 14, Number 4, 1271--1301.Abstract: Gaussian graphical models are useful tools for exploring network structures in multivariate normal data. In this paper we are interested in situations where data show departures from Gaussianity, therefore requiring alternative modeling distributions. The multivariate $t$ -distribution, obtained by dividing each component of the data vector by a gamma random variable, is a straightforward generalization to accommodate deviations from normality such as heavy tails. Since different groups of variables may be contaminated to a different extent, Finegold and Drton (2014) introduced the Dirichlet $t$ -distribution, where the divisors are clustered using a Dirichlet process. In this work, we consider a more general class of nonparametric distributions as the prior on the divisor terms, namely the class of normalized completely random measures (NormCRMs). To improve the effectiveness of the clustering, we propose modeling the dependence among the divisors through a nonparametric hierarchical structure, which allows for the sharing of parameters across the samples in the data set. This desirable feature enables us to cluster together different components of multivariate data in a parsimonious way. We demonstrate through simulations that this approach provides accurate graphical model inference, and apply it to a case study examining the dependence structure in radiomics data derived from The Cancer Imaging Atlas. Full Article
ea Spatial Disease Mapping Using Directed Acyclic Graph Auto-Regressive (DAGAR) Models By projecteuclid.org Published On :: Thu, 19 Dec 2019 22:10 EST Abhirup Datta, Sudipto Banerjee, James S. Hodges, Leiwen Gao. Source: Bayesian Analysis, Volume 14, Number 4, 1221--1244.Abstract: Hierarchical models for regionally aggregated disease incidence data commonly involve region specific latent random effects that are modeled jointly as having a multivariate Gaussian distribution. The covariance or precision matrix incorporates the spatial dependence between the regions. Common choices for the precision matrix include the widely used ICAR model, which is singular, and its nonsingular extension which lacks interpretability. We propose a new parametric model for the precision matrix based on a directed acyclic graph (DAG) representation of the spatial dependence. Our model guarantees positive definiteness and, hence, in addition to being a valid prior for regional spatially correlated random effects, can also directly model the outcome from dependent data like images and networks. Theoretical results establish a link between the parameters in our model and the variance and covariances of the random effects. Simulation studies demonstrate that the improved interpretability of our model reaps benefits in terms of accurately recovering the latent spatial random effects as well as for inference on the spatial covariance parameters. Under modest spatial correlation, our model far outperforms the CAR models, while the performances are similar when the spatial correlation is strong. We also assess sensitivity to the choice of the ordering in the DAG construction using theoretical and empirical results which testify to the robustness of our model. We also present a large-scale public health application demonstrating the competitive performance of the model. Full Article
ea Probability Based Independence Sampler for Bayesian Quantitative Learning in Graphical Log-Linear Marginal Models By projecteuclid.org Published On :: Tue, 11 Jun 2019 04:00 EDT Ioannis Ntzoufras, Claudia Tarantola, Monia Lupparelli. Source: Bayesian Analysis, Volume 14, Number 3, 797--823.Abstract: We introduce a novel Bayesian approach for quantitative learning for graphical log-linear marginal models. These models belong to curved exponential families that are difficult to handle from a Bayesian perspective. The likelihood cannot be analytically expressed as a function of the marginal log-linear interactions, but only in terms of cell counts or probabilities. Posterior distributions cannot be directly obtained, and Markov Chain Monte Carlo (MCMC) methods are needed. Finally, a well-defined model requires parameter values that lead to compatible marginal probabilities. Hence, any MCMC should account for this important restriction. We construct a fully automatic and efficient MCMC strategy for quantitative learning for such models that handles these problems. While the prior is expressed in terms of the marginal log-linear interactions, we build an MCMC algorithm that employs a proposal on the probability parameter space. The corresponding proposal on the marginal log-linear interactions is obtained via parameter transformation. We exploit a conditional conjugate setup to build an efficient proposal on probability parameters. The proposed methodology is illustrated by a simulation study and a real dataset. Full Article
ea A Bayesian Nonparametric Multiple Testing Procedure for Comparing Several Treatments Against a Control By projecteuclid.org Published On :: Fri, 31 May 2019 22:05 EDT Luis Gutiérrez, Andrés F. Barrientos, Jorge González, Daniel Taylor-Rodríguez. Source: Bayesian Analysis, Volume 14, Number 2, 649--675.Abstract: We propose a Bayesian nonparametric strategy to test for differences between a control group and several treatment regimes. Most of the existing tests for this type of comparison are based on the differences between location parameters. In contrast, our approach identifies differences across the entire distribution, avoids strong modeling assumptions over the distributions for each treatment, and accounts for multiple testing through the prior distribution on the space of hypotheses. The proposal is compared to other commonly used hypothesis testing procedures under simulated scenarios. Two real applications are also analyzed with the proposed methodology. Full Article
ea 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
ea A Tale of Two Parasites: Statistical Modelling to Support Disease Control Programmes in Africa By projecteuclid.org Published On :: Tue, 03 Mar 2020 04:00 EST Peter J. Diggle, Emanuele Giorgi, Julienne Atsame, Sylvie Ntsame Ella, Kisito Ogoussan, Katherine Gass. Source: Statistical Science, Volume 35, Number 1, 42--50.Abstract: Vector-borne diseases have long presented major challenges to the health of rural communities in the wet tropical regions of the world, but especially in sub-Saharan Africa. In this paper, we describe the contribution that statistical modelling has made to the global elimination programme for one vector-borne disease, onchocerciasis. We explain why information on the spatial distribution of a second vector-borne disease, Loa loa, is needed before communities at high risk of onchocerciasis can be treated safely with mass distribution of ivermectin, an antifiarial medication. We show how a model-based geostatistical analysis of Loa loa prevalence survey data can be used to map the predictive probability that each location in the region of interest meets a WHO policy guideline for safe mass distribution of ivermectin and describe two applications: one is to data from Cameroon that assesses prevalence using traditional blood-smear microscopy; the other is to Africa-wide data that uses a low-cost questionnaire-based method. We describe how a recent technological development in image-based microscopy has resulted in a change of emphasis from prevalence alone to the bivariate spatial distribution of prevalence and the intensity of infection among infected individuals. We discuss how statistical modelling of the kind described here can contribute to health policy guidelines and decision-making in two ways. One is to ensure that, in a resource-limited setting, prevalence surveys are designed, and the resulting data analysed, as efficiently as possible. The other is to provide an honest quantification of the uncertainty attached to any binary decision by reporting predictive probabilities that a policy-defined condition for action is or is not met. Full Article
ea Risk Models for Breast Cancer and Their Validation By projecteuclid.org Published On :: Tue, 03 Mar 2020 04:00 EST Adam R. Brentnall, Jack Cuzick. Source: Statistical Science, Volume 35, Number 1, 14--30.Abstract: Strategies to prevent cancer and diagnose it early when it is most treatable are needed to reduce the public health burden from rising disease incidence. Risk assessment is playing an increasingly important role in targeting individuals in need of such interventions. For breast cancer many individual risk factors have been well understood for a long time, but the development of a fully comprehensive risk model has not been straightforward, in part because there have been limited data where joint effects of an extensive set of risk factors may be estimated with precision. In this article we first review the approach taken to develop the IBIS (Tyrer–Cuzick) model, and describe recent updates. We then review and develop methods to assess calibration of models such as this one, where the risk of disease allowing for competing mortality over a long follow-up time or lifetime is estimated. The breast cancer risk model model and calibration assessment methods are demonstrated using a cohort of 132,139 women attending mammography screening in the State of Washington, USA. Full Article
ea Comment: “Models as Approximations I: Consequences Illustrated with Linear Regression” by A. Buja, R. Berk, L. Brown, E. George, E. Pitkin, L. Zhan and K. Zhang By projecteuclid.org Published On :: Wed, 08 Jan 2020 04:00 EST Roderick J. Little. Source: Statistical Science, Volume 34, Number 4, 580--583. Full Article
ea Models as Approximations I: Consequences Illustrated with Linear Regression By projecteuclid.org Published On :: Wed, 08 Jan 2020 04:00 EST Andreas Buja, Lawrence Brown, Richard Berk, Edward George, Emil Pitkin, Mikhail Traskin, Kai Zhang, Linda Zhao. Source: Statistical Science, Volume 34, Number 4, 523--544.Abstract: In the early 1980s, Halbert White inaugurated a “model-robust” form of statistical inference based on the “sandwich estimator” of standard error. This estimator is known to be “heteroskedasticity-consistent,” but it is less well known to be “nonlinearity-consistent” as well. Nonlinearity, however, raises fundamental issues because in its presence regressors are not ancillary, hence cannot be treated as fixed. The consequences are deep: (1) population slopes need to be reinterpreted as statistical functionals obtained from OLS fits to largely arbitrary joint ${x extrm{-}y}$ distributions; (2) the meaning of slope parameters needs to be rethought; (3) the regressor distribution affects the slope parameters; (4) randomness of the regressors becomes a source of sampling variability in slope estimates of order $1/sqrt{N}$; (5) inference needs to be based on model-robust standard errors, including sandwich estimators or the ${x extrm{-}y}$ bootstrap. In theory, model-robust and model-trusting standard errors can deviate by arbitrary magnitudes either way. In practice, significant deviations between them can be detected with a diagnostic test. Full Article
ea Assessing the Causal Effect of Binary Interventions from Observational Panel Data with Few Treated Units By projecteuclid.org Published On :: Fri, 11 Oct 2019 04:03 EDT Pantelis Samartsidis, Shaun R. Seaman, Anne M. Presanis, Matthew Hickman, Daniela De Angelis. Source: Statistical Science, Volume 34, Number 3, 486--503.Abstract: Researchers are often challenged with assessing the impact of an intervention on an outcome of interest in situations where the intervention is nonrandomised, the intervention is only applied to one or few units, the intervention is binary, and outcome measurements are available at multiple time points. In this paper, we review existing methods for causal inference in these situations. We detail the assumptions underlying each method, emphasize connections between the different approaches and provide guidelines regarding their practical implementation. Several open problems are identified thus highlighting the need for future research. Full Article
ea Conditionally Conjugate Mean-Field Variational Bayes for Logistic Models By projecteuclid.org Published On :: Fri, 11 Oct 2019 04:03 EDT Daniele Durante, Tommaso Rigon. Source: Statistical Science, Volume 34, Number 3, 472--485.Abstract: Variational Bayes (VB) is a common strategy for approximate Bayesian inference, but simple methods are only available for specific classes of models including, in particular, representations having conditionally conjugate constructions within an exponential family. Models with logit components are an apparently notable exception to this class, due to the absence of conjugacy among the logistic likelihood and the Gaussian priors for the coefficients in the linear predictor. To facilitate approximate inference within this widely used class of models, Jaakkola and Jordan ( Stat. Comput. 10 (2000) 25–37) proposed a simple variational approach which relies on a family of tangent quadratic lower bounds of the logistic log-likelihood, thus restoring conjugacy between these approximate bounds and the Gaussian priors. This strategy is still implemented successfully, but few attempts have been made to formally understand the reasons underlying its excellent performance. Following a review on VB for logistic models, we cover this gap by providing a formal connection between the above bound and a recent Pólya-gamma data augmentation for logistic regression. Such a result places the computational methods associated with the aforementioned bounds within the framework of variational inference for conditionally conjugate exponential family models, thereby allowing recent advances for this class to be inherited also by the methods relying on Jaakkola and Jordan ( Stat. Comput. 10 (2000) 25–37). Full Article
ea User-Friendly Covariance Estimation for Heavy-Tailed Distributions By projecteuclid.org Published On :: Fri, 11 Oct 2019 04:03 EDT Yuan Ke, Stanislav Minsker, Zhao Ren, Qiang Sun, Wen-Xin Zhou. Source: Statistical Science, Volume 34, Number 3, 454--471.Abstract: We provide a survey of recent results on covariance estimation for heavy-tailed distributions. By unifying ideas scattered in the literature, we propose user-friendly methods that facilitate practical implementation. Specifically, we introduce elementwise and spectrumwise truncation operators, as well as their $M$-estimator counterparts, to robustify the sample covariance matrix. Different from the classical notion of robustness that is characterized by the breakdown property, we focus on the tail robustness which is evidenced by the connection between nonasymptotic deviation and confidence level. The key insight is that estimators should adapt to the sample size, dimensionality and noise level to achieve optimal tradeoff between bias and robustness. Furthermore, to facilitate practical implementation, we propose data-driven procedures that automatically calibrate the tuning parameters. We demonstrate their applications to a series of structured models in high dimensions, including the bandable and low-rank covariance matrices and sparse precision matrices. Numerical studies lend strong support to the proposed methods. Full Article
ea A Kernel Regression Procedure in the 3D Shape Space with an Application to Online Sales of Children’s Wear By projecteuclid.org Published On :: Thu, 18 Jul 2019 22:01 EDT Gregorio Quintana-Ortí, Amelia Simó. Source: Statistical Science, Volume 34, Number 2, 236--252.Abstract: This paper is focused on kernel regression when the response variable is the shape of a 3D object represented by a configuration matrix of landmarks. Regression methods on this shape space are not trivial because this space has a complex finite-dimensional Riemannian manifold structure (non-Euclidean). Papers about it are scarce in the literature, the majority of them are restricted to the case of a single explanatory variable, and many of them are based on the approximated tangent space. In this paper, there are several methodological innovations. The first one is the adaptation of the general method for kernel regression analysis in manifold-valued data to the three-dimensional case of Kendall’s shape space. The second one is its generalization to the multivariate case and the addressing of the curse-of-dimensionality problem. Finally, we propose bootstrap confidence intervals for prediction. A simulation study is carried out to check the goodness of the procedure, and a comparison with a current approach is performed. Then, it is applied to a 3D database obtained from an anthropometric survey of the Spanish child population with a potential application to online sales of children’s wear. Full Article
ea Comment: Empirical Bayes, Compound Decisions and Exchangeability By projecteuclid.org Published On :: Thu, 18 Jul 2019 22:01 EDT Eitan Greenshtein, Ya’acov Ritov. Source: Statistical Science, Volume 34, Number 2, 224--228.Abstract: We present some personal reflections on empirical Bayes/ compound decision (EB/CD) theory following Efron (2019). In particular, we consider the role of exchangeability in the EB/CD theory and how it can be achieved when there are covariates. We also discuss the interpretation of EB/CD confidence interval, the theoretical efficiency of the CD procedure, and the impact of sparsity assumptions. Full Article
ea Gaussian Integrals and Rice Series in Crossing Distributions—to Compute the Distribution of Maxima and Other Features of Gaussian Processes By projecteuclid.org Published On :: Fri, 12 Apr 2019 04:00 EDT Georg Lindgren. Source: Statistical Science, Volume 34, Number 1, 100--128.Abstract: We describe and compare how methods based on the classical Rice’s formula for the expected number, and higher moments, of level crossings by a Gaussian process stand up to contemporary numerical methods to accurately deal with crossing related characteristics of the sample paths. We illustrate the relative merits in accuracy and computing time of the Rice moment methods and the exact numerical method, developed since the late 1990s, on three groups of distribution problems, the maximum over a finite interval and the waiting time to first crossing, the length of excursions over a level, and the joint period/amplitude of oscillations. We also treat the notoriously difficult problem of dependence between successive zero crossing distances. The exact solution has been known since at least 2000, but it has remained largely unnoticed outside the ocean science community. Extensive simulation studies illustrate the accuracy of the numerical methods. As a historical introduction an attempt is made to illustrate the relation between Rice’s original formulation and arguments and the exact numerical methods. Full Article
ea Rejoinder: Response to Discussions and a Look Ahead By projecteuclid.org Published On :: Fri, 12 Apr 2019 04:00 EDT Vincent Dorie, Jennifer Hill, Uri Shalit, Marc Scott, Dan Cervone. Source: Statistical Science, Volume 34, Number 1, 94--99.Abstract: Response to discussion of Dorie (2017), in which the authors of that piece express their gratitude to the discussants, rebut some specific criticisms, and argue that the limitations of the 2016 Atlantic Causal Inference Competition represent an exciting opportunity for future competitions in a similar mold. Full Article
ea Comment: Contributions of Model Features to BART Causal Inference Performance Using ACIC 2016 Competition Data By projecteuclid.org Published On :: Fri, 12 Apr 2019 04:00 EDT Nicole Bohme Carnegie. Source: Statistical Science, Volume 34, Number 1, 90--93.Abstract: With a thorough exposition of the methods and results of the 2016 Atlantic Causal Inference Competition, Dorie et al. have set a new standard for reproducibility and comparability of evaluations of causal inference methods. In particular, the open-source R package aciccomp2016, which permits reproduction of all datasets used in the competition, will be an invaluable resource for evaluation of future methodological developments. Building upon results from Dorie et al., we examine whether a set of potential modifications to Bayesian Additive Regression Trees (BART)—multiple chains in model fitting, using the propensity score as a covariate, targeted maximum likelihood estimation (TMLE), and computing symmetric confidence intervals—have a stronger impact on bias, RMSE, and confidence interval coverage in combination than they do alone. We find that bias in the estimate of SATT is minimal, regardless of the BART formulation. For purposes of CI coverage, however, all proposed modifications are beneficial—alone and in combination—but use of TMLE is least beneficial for coverage and results in considerably wider confidence intervals. Full Article
ea Comment on “Automated Versus Do-It-Yourself Methods for Causal Inference: Lessons Learned from a Data Analysis Competition” By projecteuclid.org Published On :: Fri, 12 Apr 2019 04:00 EDT Susan Gruber, Mark J. van der Laan. Source: Statistical Science, Volume 34, Number 1, 82--85.Abstract: Dorie and co-authors (DHSSC) are to be congratulated for initiating the ACIC Data Challenge. Their project engaged the community and accelerated research by providing a level playing field for comparing the performance of a priori specified algorithms. DHSSC identified themes concerning characteristics of the DGP, properties of the estimators, and inference. We discuss these themes in the context of targeted learning. Full Article
ea Heteromodal Cortical Areas Encode Sensory-Motor Features of Word Meaning By www.jneurosci.org Published On :: 2016-09-21T09:33:18-07:00 The capacity to process information in conceptual form is a fundamental aspect of human cognition, yet little is known about how this type of information is encoded in the brain. Although the role of sensory and motor cortical areas has been a focus of recent debate, neuroimaging studies of concept representation consistently implicate a network of heteromodal areas that seem to support concept retrieval in general rather than knowledge related to any particular sensory-motor content. We used predictive machine learning on fMRI data to investigate the hypothesis that cortical areas in this "general semantic network" (GSN) encode multimodal information derived from basic sensory-motor processes, possibly functioning as convergence–divergence zones for distributed concept representation. An encoding model based on five conceptual attributes directly related to sensory-motor experience (sound, color, shape, manipulability, and visual motion) was used to predict brain activation patterns associated with individual lexical concepts in a semantic decision task. When the analysis was restricted to voxels in the GSN, the model was able to identify the activation patterns corresponding to individual concrete concepts significantly above chance. In contrast, a model based on five perceptual attributes of the word form performed at chance level. This pattern was reversed when the analysis was restricted to areas involved in the perceptual analysis of written word forms. These results indicate that heteromodal areas involved in semantic processing encode information about the relative importance of different sensory-motor attributes of concepts, possibly by storing particular combinations of sensory and motor features. SIGNIFICANCE STATEMENT The present study used a predictive encoding model of word semantics to decode conceptual information from neural activity in heteromodal cortical areas. The model is based on five sensory-motor attributes of word meaning (color, shape, sound, visual motion, and manipulability) and encodes the relative importance of each attribute to the meaning of a word. This is the first demonstration that heteromodal areas involved in semantic processing can discriminate between different concepts based on sensory-motor information alone. This finding indicates that the brain represents concepts as multimodal combinations of sensory and motor representations. Full Article
ea Cleanair not smoke / design : Biman Mullick. By search.wellcomelibrary.org Published On :: London : Cleanair, Smoke-free Environment (33 Stillness Rd, London, SE23 1NG), [198-?] Full Article
ea Heart burn. / design : Biman Mullick. By search.wellcomelibrary.org Published On :: London : Cleanair, Smoke-free Environment (33 Stillness Rd, London, SE23 1NG), [198-?] Full Article
ea दिल की जलन। = Heart burn. / design : Biman Mullick. By search.wellcomelibrary.org Published On :: London : Cleanair (33 Stillness Rd, London, SE23 1NG), [1989?] Full Article
ea Dila jalana = Heart burn. / design : Biman Mullick. By search.wellcomelibrary.org Published On :: London : Cleanair (33 Stillness Rd, London, SE23 1NG), [198-?] Full Article
ea Hārtabarna = Heart burn. / design : Biman Mullick. By search.wellcomelibrary.org Published On :: London : Cleanair (33 Stillness Rd, London, SE23 1NG), [198-?] Full Article