sem Silence is consent / Rosemary Winderlich. By www.catalog.slsa.sa.gov.au Published On :: Full Article
sem Probate rules : preparing grants of probate & letters of administration / paper presented by Rosemary Caruso, Tindall Gask Bentley. By www.catalog.slsa.sa.gov.au Published On :: Full Article
sem Probate rules : preparing grants of probate & letters of administration / paper presented by Rosemary Caruso, Tindall Gask Bentley. By www.catalog.slsa.sa.gov.au Published On :: Full Article
sem The four horsemen : the discussion that sparked an atheist revolution / Dawkins, Harris, Dennett, Hitchens ; foreword by Stephen Fry. By www.catalog.slsa.sa.gov.au Published On :: Dawkins, Richard, 1941- -- Religion. Full Article
sem Des pressions centripetes (Epreuve de Gelle) etude de semeiologie auriculaire / par Le Docteur Georges Gelle. By feedproxy.google.com Published On :: Paris : Société d’éditions scientifiques, 1895. Full Article
sem Des rétrécissements du canal de l'urèthre / par Édouard de Smet. By feedproxy.google.com Published On :: Bruxelles : H. Manceux, 1880. Full Article
sem Die Mneme : als erhaltendes Prinzip im Wechsel des organischen Geschehens / von Richard Semon. By feedproxy.google.com Published On :: Leipzig : Engelmann, 1904. Full Article
sem Die Rhinoskopie und ihr Werth für die ärztliche Praxis : ein monographischer Versuch / von Friedrich Semeleder. By feedproxy.google.com Published On :: Leipzig : W. Engelmann, 1862. Full Article
sem Die Schwindsucht im Lichte der Statistik und Socialpolitik : mit besonderer Berücksichtigung der staatlichen und privaten Versicherung ; eine Arbeit aus dem königlichen Versicherungsseminar der Universität Göttingen / von Wilhelm Kley. By feedproxy.google.com Published On :: Leipzig : Duncker & Humblot, 1898. Full Article
sem Die Verwandtschaftsbeziehungen der gegliederten Thiere / von C. Semper. By feedproxy.google.com Published On :: Wurzburg : Druck und Verlag, 1875. Full Article
sem The diseases of children : a handbook for practitioners and students / by Armand Semple. By feedproxy.google.com Published On :: London : Bailliere, Tindall, & Cox, 1884. Full Article
sem Doubts about Darwinism / by a Semi-Darwinian. By feedproxy.google.com Published On :: London : Longmans, Green, 1903. Full Article
sem Du curettage de l'utérus sans abaissement forcé à la vulve et d'une méthode de drainage utérin au moyen du crin de Florence / par Prosper Bouteil. By feedproxy.google.com Published On :: Paris : Société d’éditions scientifiques, 1893. Full Article
sem Du retrécissement cicatriciel du col de l'utérus au point de vue de l'accouchement / par Victor-Albert Taurin. By feedproxy.google.com Published On :: Paris : G. Steinheil, 1895. Full Article
sem Emphyseme pulmonaire / par le Dr Despréaux. By feedproxy.google.com Published On :: Paris : Rueff, 1896. Full Article
sem Epidemische Erkrankungen an akutem Exanthem mit typhösem Charakter in der Garnison Cosel / von Dr. Schulte. By feedproxy.google.com Published On :: Berlin : A. Hirschwald, 1893. Full Article
sem Erkenntniß und Behandlung der Frauenkrankheiten im allgemeinen : 4 Vorträge, in d. Gynäkolog. Klinik zu Kiel im Sommer-Semester 1885 / gehalten von Carl Conrad Theodor Litzmann. By feedproxy.google.com Published On :: Berlin : Hirschwald, 1886. Full Article
sem Essai sur la semeiologie du pouls en clinique chirurgicale / par Francois Bertonnier. By feedproxy.google.com Published On :: Paris : G. Steinheil, 1895. Full Article
sem Essai sur le rétrécissement tricuspidien / Robert Leudet. By feedproxy.google.com Published On :: Paris : Steinheil, 1888. Full Article
sem Florida Passes Anti-Semitism Bill for Public Schools By feedproxy.google.com Published On :: Fri, 03 May 2019 00:00:00 +0000 A bill prohibiting anti-Semitism in Florida's public schools and universities is going to Republican Gov. Ron DeSantis. Full Article Florida
sem Florida teachers union wants schools closed for the semester By feedproxy.google.com Published On :: Wed, 15 Apr 2020 00:00:00 +0000 Full Article Florida
sem Governor: Mississippi schools remain closed rest of semester By feedproxy.google.com Published On :: Wed, 15 Apr 2020 00:00:00 +0000 Full Article Mississippi
sem A Moroccan horseman setting off with a rifle to perform at an equestrian display (fantasia, Tbourida). Etching and drypoint by L.A. Lecouteux after H. Regnault, 1870. By feedproxy.google.com Published On :: Full Article
sem An ensemble of Burmese musicians playing traditional instruments at a local funeral. Wood engraving after H.G. Robley. By feedproxy.google.com Published On :: Full Article
sem An ensemble of Burmese musicians playing traditional instruments at a local funeral. Wood engraving after H.G. Robley. By feedproxy.google.com Published On :: Full Article
sem Pritzker orders Illinois schools closed for rest of semester By feedproxy.google.com Published On :: Mon, 20 Apr 2020 00:00:00 +0000 Full Article Illinois
sem 2020 NHL draft profile: Braden Schneider has quite a high ceiling for a 2-way defenseman By sports.yahoo.com Published On :: Thu, 07 May 2020 14:32:18 GMT The Flyers have had quite a bit of luck when drafting players from the Brandon Wheat Kings. Could they keep their streak alive with Braden Schneider in the first round of the 2020 NHL draft? By Brooke Destra Full Article article News
sem Adaptive estimation in the supremum norm for semiparametric mixtures of regressions By projecteuclid.org Published On :: Thu, 23 Apr 2020 22:01 EDT Heiko Werner, Hajo Holzmann, Pierre Vandekerkhove. Source: Electronic Journal of Statistics, Volume 14, Number 1, 1816--1871.Abstract: We investigate a flexible two-component semiparametric mixture of regressions model, in which one of the conditional component distributions of the response given the covariate is unknown but assumed symmetric about a location parameter, while the other is specified up to a scale parameter. The location and scale parameters together with the proportion are allowed to depend nonparametrically on covariates. After settling identifiability, we provide local M-estimators for these parameters which converge in the sup-norm at the optimal rates over Hölder-smoothness classes. We also introduce an adaptive version of the estimators based on the Lepski-method. Sup-norm bounds show that the local M-estimator properly estimates the functions globally, and are the first step in the construction of useful inferential tools such as confidence bands. In our analysis we develop general results about rates of convergence in the sup-norm as well as adaptive estimation of local M-estimators which might be of some independent interest, and which can also be applied in various other settings. We investigate the finite-sample behaviour of our method in a simulation study, and give an illustration to a real data set from bioinformatics. Full Article
sem Estimation of a semiparametric transformation model: A novel approach based on least squares minimization By projecteuclid.org Published On :: Tue, 04 Feb 2020 22:03 EST Benjamin Colling, Ingrid Van Keilegom. Source: Electronic Journal of Statistics, Volume 14, Number 1, 769--800.Abstract: Consider the following semiparametric transformation model $Lambda_{ heta }(Y)=m(X)+varepsilon $, where $X$ is a $d$-dimensional covariate, $Y$ is a univariate response variable and $varepsilon $ is an error term with zero mean and independent of $X$. We assume that $m$ is an unknown regression function and that ${Lambda _{ heta }: heta inTheta }$ is a parametric family of strictly increasing functions. Our goal is to develop two new estimators of the transformation parameter $ heta $. The main idea of these two estimators is to minimize, with respect to $ heta $, the $L_{2}$-distance between the transformation $Lambda _{ heta }$ and one of its fully nonparametric estimators. We consider in particular the nonparametric estimator based on the least-absolute deviation loss constructed in Colling and Van Keilegom (2019). We establish the consistency and the asymptotic normality of the two proposed estimators of $ heta $. We also carry out a simulation study to illustrate and compare the performance of our new parametric estimators to that of the profile likelihood estimator constructed in Linton et al. (2008). Full Article
sem DESlib: A Dynamic ensemble selection library in Python By Published On :: 2020 DESlib is an open-source python library providing the implementation of several dynamic selection techniques. The library is divided into three modules: (i) dcs, containing the implementation of dynamic classifier selection methods (DCS); (ii) des, containing the implementation of dynamic ensemble selection methods (DES); (iii) static, with the implementation of static ensemble techniques. The library is fully documented (documentation available online on Read the Docs), has a high test coverage (codecov.io) and is part of the scikit-learn-contrib supported projects. Documentation, code and examples can be found on its GitHub page: https://github.com/scikit-learn-contrib/DESlib. Full Article
sem On the consistency of graph-based Bayesian semi-supervised learning and the scalability of sampling algorithms By Published On :: 2020 This paper considers a Bayesian approach to graph-based semi-supervised learning. We show that if the graph parameters are suitably scaled, the graph-posteriors converge to a continuum limit as the size of the unlabeled data set grows. This consistency result has profound algorithmic implications: we prove that when consistency holds, carefully designed Markov chain Monte Carlo algorithms have a uniform spectral gap, independent of the number of unlabeled inputs. Numerical experiments illustrate and complement the theory. Full Article
sem Ensemble Learning for Relational Data By Published On :: 2020 We present a theoretical analysis framework for relational ensemble models. We show that ensembles of collective classifiers can improve predictions for graph data by reducing errors due to variance in both learning and inference. In addition, we propose a relational ensemble framework that combines a relational ensemble learning approach with a relational ensemble inference approach for collective classification. The proposed ensemble techniques are applicable for both single and multiple graph settings. Experiments on both synthetic and real-world data demonstrate the effectiveness of the proposed framework. Finally, our experimental results support the theoretical analysis and confirm that ensemble algorithms that explicitly focus on both learning and inference processes and aim at reducing errors associated with both, are the best performers. Full Article
sem Effects of gene–environment and gene–gene interactions in case-control studies: A novel Bayesian semiparametric approach By projecteuclid.org Published On :: Mon, 03 Feb 2020 04:00 EST Durba Bhattacharya, Sourabh Bhattacharya. Source: Brazilian Journal of Probability and Statistics, Volume 34, Number 1, 71--89.Abstract: Present day bio-medical research is pointing towards the fact that cognizance of gene–environment interactions along with genetic interactions may help prevent or detain the onset of many complex diseases like cardiovascular disease, cancer, type2 diabetes, autism or asthma by adjustments to lifestyle. In this regard, we propose a Bayesian semiparametric model to detect not only the roles of genes and their interactions, but also the possible influence of environmental variables on the genes in case-control studies. Our model also accounts for the unknown number of genetic sub-populations via finite mixtures composed of Dirichlet processes. An effective parallel computing methodology, developed by us harnesses the power of parallel processing technology to increase the efficiencies of our conditionally independent Gibbs sampling and Transformation based MCMC (TMCMC) methods. Applications of our model and methods to simulation studies with biologically realistic genotype datasets and a real, case-control based genotype dataset on early onset of myocardial infarction (MI) have yielded quite interesting results beside providing some insights into the differential effect of gender on MI. Full Article
sem Semi-parametric estimation for conditional independence multivariate finite mixture models By projecteuclid.org Published On :: Fri, 06 Feb 2015 08:39 EST Didier Chauveau, David R. Hunter, Michael Levine. Source: Statistics Surveys, Volume 9, 1--31.Abstract: The conditional independence assumption for nonparametric multivariate finite mixture models, a weaker form of the well-known conditional independence assumption for random effects models for longitudinal data, is the subject of an increasing number of theoretical and algorithmic developments in the statistical literature. After presenting a survey of this literature, including an in-depth discussion of the all-important identifiability results, this article describes and extends an algorithm for estimation of the parameters in these models. The algorithm works for any number of components in three or more dimensions. It possesses a descent property and can be easily adapted to situations where the data are grouped in blocks of conditionally independent variables. We discuss how to adapt this algorithm to various location-scale models that link component densities, and we even adapt it to a particular class of univariate mixture problems in which the components are assumed symmetric. We give a bandwidth selection procedure for our algorithm. Finally, we demonstrate the effectiveness of our algorithm using a simulation study and two psychometric datasets. Full Article
sem Semiparametric Optimal Estimation With Nonignorable Nonresponse Data. (arXiv:1612.09207v3 [stat.ME] UPDATED) By arxiv.org Published On :: When the response mechanism is believed to be not missing at random (NMAR), a valid analysis requires stronger assumptions on the response mechanism than standard statistical methods would otherwise require. Semiparametric estimators have been developed under the model assumptions on the response mechanism. In this paper, a new statistical test is proposed to guarantee model identifiability without using any instrumental variable. Furthermore, we develop optimal semiparametric estimation for parameters such as the population mean. Specifically, we propose two semiparametric optimal estimators that do not require any model assumptions other than the response mechanism. Asymptotic properties of the proposed estimators are discussed. An extensive simulation study is presented to compare with some existing methods. We present an application of our method using Korean Labor and Income Panel Survey data. Full Article
sem Local Cascade Ensemble for Multivariate Data Classification. (arXiv:2005.03645v1 [cs.LG]) By arxiv.org Published On :: We present LCE, a Local Cascade Ensemble for traditional (tabular) multivariate data classification, and its extension LCEM for Multivariate Time Series (MTS) classification. LCE is a new hybrid ensemble method that combines an explicit boosting-bagging approach to handle the usual bias-variance tradeoff faced by machine learning models and an implicit divide-and-conquer approach to individualize classifier errors on different parts of the training data. Our evaluation firstly shows that the hybrid ensemble method LCE outperforms the state-of-the-art classifiers on the UCI datasets and that LCEM outperforms the state-of-the-art MTS classifiers on the UEA datasets. Furthermore, LCEM provides explainability by design and manifests robust performance when faced with challenges arising from continuous data collection (different MTS length, missing data and noise). Full Article
sem Predictive Modeling of ICU Healthcare-Associated Infections from Imbalanced Data. Using Ensembles and a Clustering-Based Undersampling Approach. (arXiv:2005.03582v1 [cs.LG]) By arxiv.org Published On :: Early detection of patients vulnerable to infections acquired in the hospital environment is a challenge in current health systems given the impact that such infections have on patient mortality and healthcare costs. This work is focused on both the identification of risk factors and the prediction of healthcare-associated infections in intensive-care units by means of machine-learning methods. The aim is to support decision making addressed at reducing the incidence rate of infections. In this field, it is necessary to deal with the problem of building reliable classifiers from imbalanced datasets. We propose a clustering-based undersampling strategy to be used in combination with ensemble classifiers. A comparative study with data from 4616 patients was conducted in order to validate our proposal. We applied several single and ensemble classifiers both to the original dataset and to data preprocessed by means of different resampling methods. The results were analyzed by means of classic and recent metrics specifically designed for imbalanced data classification. They revealed that the proposal is more efficient in comparison with other approaches. Full Article
sem Sequential Aggregation of Probabilistic Forecasts -- Applicaton to Wind Speed Ensemble Forecasts. (arXiv:2005.03540v1 [stat.AP]) By arxiv.org Published On :: In the field of numerical weather prediction (NWP), the probabilistic distribution of the future state of the atmosphere is sampled with Monte-Carlo-like simulations, called ensembles. These ensembles have deficiencies (such as conditional biases) that can be corrected thanks to statistical post-processing methods. Several ensembles exist and may be corrected with different statistiscal methods. A further step is to combine these raw or post-processed ensembles. The theory of prediction with expert advice allows us to build combination algorithms with theoretical guarantees on the forecast performance. This article adapts this theory to the case of probabilistic forecasts issued as step-wise cumulative distribution functions (CDF). The theory is applied to wind speed forecasting, by combining several raw or post-processed ensembles, considered as CDFs. The second goal of this study is to explore the use of two forecast performance criteria: the Continous ranked probability score (CRPS) and the Jolliffe-Primo test. Comparing the results obtained with both criteria leads to reconsidering the usual way to build skillful probabilistic forecasts, based on the minimization of the CRPS. Minimizing the CRPS does not necessarily produce reliable forecasts according to the Jolliffe-Primo test. The Jolliffe-Primo test generally selects reliable forecasts, but could lead to issuing suboptimal forecasts in terms of CRPS. It is proposed to use both criterion to achieve reliable and skillful probabilistic forecasts. Full Article
sem Reference and Document Aware Semantic Evaluation Methods for Korean Language Summarization. (arXiv:2005.03510v1 [cs.CL]) By arxiv.org Published On :: Text summarization refers to the process that generates a shorter form of text from the source document preserving salient information. Recently, many models for text summarization have been proposed. Most of those models were evaluated using recall-oriented understudy for gisting evaluation (ROUGE) scores. However, as ROUGE scores are computed based on n-gram overlap, they do not reflect semantic meaning correspondences between generated and reference summaries. Because Korean is an agglutinative language that combines various morphemes into a word that express several meanings, ROUGE is not suitable for Korean summarization. In this paper, we propose evaluation metrics that reflect semantic meanings of a reference summary and the original document, Reference and Document Aware Semantic Score (RDASS). We then propose a method for improving the correlation of the metrics with human judgment. Evaluation results show that the correlation with human judgment is significantly higher for our evaluation metrics than for ROUGE scores. Full Article
sem Transfer Learning for sEMG-based Hand Gesture Classification using Deep Learning in a Master-Slave Architecture. (arXiv:2005.03460v1 [eess.SP]) By arxiv.org Published On :: Recent advancements in diagnostic learning and development of gesture-based human machine interfaces have driven surface electromyography (sEMG) towards significant importance. Analysis of hand gestures requires an accurate assessment of sEMG signals. The proposed work presents a novel sequential master-slave architecture consisting of deep neural networks (DNNs) for classification of signs from the Indian sign language using signals recorded from multiple sEMG channels. The performance of the master-slave network is augmented by leveraging additional synthetic feature data generated by long short term memory networks. Performance of the proposed network is compared to that of a conventional DNN prior to and after the addition of synthetic data. Up to 14% improvement is observed in the conventional DNN and up to 9% improvement in master-slave network on addition of synthetic data with an average accuracy value of 93.5% asserting the suitability of the proposed approach. Full Article
sem lslx: Semi-Confirmatory Structural Equation Modeling via Penalized Likelihood By www.jstatsoft.org Published On :: Mon, 27 Apr 2020 00:00:00 +0000 Sparse estimation via penalized likelihood (PL) is now a popular approach to learn the associations among a large set of variables. This paper describes an R package called lslx that implements PL methods for semi-confirmatory structural equation modeling (SEM). In this semi-confirmatory approach, each model parameter can be specified as free/fixed for theory testing, or penalized for exploration. By incorporating either a L1 or minimax concave penalty, the sparsity pattern of the parameter matrix can be efficiently explored. Package lslx minimizes the PL criterion through a quasi-Newton method. The algorithm conducts line search and checks the first-order condition in each iteration to ensure the optimality of the obtained solution. A numerical comparison between competing packages shows that lslx can reliably find PL estimates with the least time. The current package also supports other advanced functionalities, including a two-stage method with auxiliary variables for missing data handling and a reparameterized multi-group SEM to explore population heterogeneity. Full Article
sem Semi-Parametric Joint Modeling of Survival and Longitudinal Data: The R Package JSM By www.jstatsoft.org Published On :: Sat, 18 Apr 2020 03:35:08 +0000 This paper is devoted to the R package JSM which performs joint statistical modeling of survival and longitudinal data. In biomedical studies it has been increasingly common to collect both baseline and longitudinal covariates along with a possibly censored survival time. Instead of analyzing the survival and longitudinal outcomes separately, joint modeling approaches have attracted substantive attention in the recent literature and have been shown to correct biases from separate modeling approaches and enhance information. Most existing approaches adopt a linear mixed effects model for the longitudinal component and the Cox proportional hazards model for the survival component. We extend the Cox model to a more general class of transformation models for the survival process, where the baseline hazard function is completely unspecified leading to semiparametric survival models. We also offer a non-parametric multiplicative random effects model for the longitudinal process in JSM in addition to the linear mixed effects model. In this paper, we present the joint modeling framework that is implemented in JSM, as well as the standard error estimation methods, and illustrate the package with two real data examples: a liver cirrhosis data and a Mayo Clinic primary biliary cirrhosis data. Full Article
sem History of Pre-Modern Medicine Seminar Series, Spring 2018 By blog.wellcomelibrary.org Published On :: Fri, 05 Jan 2018 12:26:55 +0000 The History of Pre-Modern Medicine seminar series returns this month. The 2017–18 series – organised by a group of historians of medicine based at London universities and hosted by the Wellcome Library – will conclude with four seminars. The series… Continue reading Full Article Early Medicine Events and Visits China Early Sex and Reproduction plague smell
sem Semantic technology : 9th Joint International Conference, JIST 2019, Hangzhou, China, November 25-27, 2019, Revised selected papers By dal.novanet.ca Published On :: Fri, 1 May 2020 19:44:43 -0300 Author: Joint International Semantic Technology Conference (9th : 2019 : Hangzhou, China)Callnumber: OnlineISBN: 9789811534126 (electronic bk.) Full Article
sem Two-step semiparametric empirical likelihood inference By projecteuclid.org Published On :: Mon, 17 Feb 2020 04:02 EST Francesco Bravo, Juan Carlos Escanciano, Ingrid Van Keilegom. Source: The Annals of Statistics, Volume 48, Number 1, 1--26.Abstract: In both parametric and certain nonparametric statistical models, the empirical likelihood ratio satisfies a nonparametric version of Wilks’ theorem. For many semiparametric models, however, the commonly used two-step (plug-in) empirical likelihood ratio is not asymptotically distribution-free, that is, its asymptotic distribution contains unknown quantities, and hence Wilks’ theorem breaks down. This article suggests a general approach to restore Wilks’ phenomenon in two-step semiparametric empirical likelihood inferences. The main insight consists in using as the moment function in the estimating equation the influence function of the plug-in sample moment. The proposed method is general; it leads to a chi-squared limiting distribution with known degrees of freedom; it is efficient; it does not require undersmoothing; and it is less sensitive to the first-step than alternative methods, which is particularly appealing for high-dimensional settings. Several examples and simulation studies illustrate the general applicability of the procedure and its excellent finite sample performance relative to competing methods. Full Article
sem Semiparametrically point-optimal hybrid rank tests for unit roots By projecteuclid.org Published On :: Fri, 02 Aug 2019 22:04 EDT Bo Zhou, Ramon van den Akker, Bas J. M. Werker. Source: The Annals of Statistics, Volume 47, Number 5, 2601--2638.Abstract: We propose a new class of unit root tests that exploits invariance properties in the Locally Asymptotically Brownian Functional limit experiment associated to the unit root model. The invariance structures naturally suggest tests that are based on the ranks of the increments of the observations, their average and an assumed reference density for the innovations. The tests are semiparametric in the sense that they are valid, that is, have the correct (asymptotic) size, irrespective of the true innovation density. For a correctly specified reference density, our test is point-optimal and nearly efficient. For arbitrary reference densities, we establish a Chernoff–Savage-type result, that is, our test performs as well as commonly used tests under Gaussian innovations but has improved power under other, for example, fat-tailed or skewed, innovation distributions. To avoid nonparametric estimation, we propose a simplified version of our test that exhibits the same asymptotic properties, except for the Chernoff–Savage result that we are only able to demonstrate by means of simulations. Full Article
sem Semi-supervised inference: General theory and estimation of means By projecteuclid.org Published On :: Fri, 02 Aug 2019 22:04 EDT Anru Zhang, Lawrence D. Brown, T. Tony Cai. Source: The Annals of Statistics, Volume 47, Number 5, 2538--2566.Abstract: We propose a general semi-supervised inference framework focused on the estimation of the population mean. As usual in semi-supervised settings, there exists an unlabeled sample of covariate vectors and a labeled sample consisting of covariate vectors along with real-valued responses (“labels”). Otherwise, the formulation is “assumption-lean” in that no major conditions are imposed on the statistical or functional form of the data. We consider both the ideal semi-supervised setting where infinitely many unlabeled samples are available, as well as the ordinary semi-supervised setting in which only a finite number of unlabeled samples is available. Estimators are proposed along with corresponding confidence intervals for the population mean. Theoretical analysis on both the asymptotic distribution and $ell_{2}$-risk for the proposed procedures are given. Surprisingly, the proposed estimators, based on a simple form of the least squares method, outperform the ordinary sample mean. The simple, transparent form of the estimator lends confidence to the perception that its asymptotic improvement over the ordinary sample mean also nearly holds even for moderate size samples. The method is further extended to a nonparametric setting, in which the oracle rate can be achieved asymptotically. The proposed estimators are further illustrated by simulation studies and a real data example involving estimation of the homeless population. Full Article
sem semantics By looselycoupled.com Published On :: 2006-01-02T14:00:00-00:00 Intended meaning. In computing, semantics is the assumed or explicit set of understandings used in a system to give meaning to data. One of the biggest challenges when integrating separate computer systems and applications is to correctly match up the intended meanings within each system. Simple metadata classifications such as 'price' or 'location' may have wildly different meanings in each system, while apparently different terms, such as 'client' and 'patient' may turn out to be effectively equivalent. Full Article
sem Estimating the health effects of environmental mixtures using Bayesian semiparametric regression and sparsity inducing priors By projecteuclid.org Published On :: Wed, 15 Apr 2020 22:05 EDT Joseph Antonelli, Maitreyi Mazumdar, David Bellinger, David Christiani, Robert Wright, Brent Coull. Source: The Annals of Applied Statistics, Volume 14, Number 1, 257--275.Abstract: Humans are routinely exposed to mixtures of chemical and other environmental factors, making the quantification of health effects associated with environmental mixtures a critical goal for establishing environmental policy sufficiently protective of human health. The quantification of the effects of exposure to an environmental mixture poses several statistical challenges. It is often the case that exposure to multiple pollutants interact with each other to affect an outcome. Further, the exposure-response relationship between an outcome and some exposures, such as some metals, can exhibit complex, nonlinear forms, since some exposures can be beneficial and detrimental at different ranges of exposure. To estimate the health effects of complex mixtures, we propose a flexible Bayesian approach that allows exposures to interact with each other and have nonlinear relationships with the outcome. We induce sparsity using multivariate spike and slab priors to determine which exposures are associated with the outcome and which exposures interact with each other. The proposed approach is interpretable, as we can use the posterior probabilities of inclusion into the model to identify pollutants that interact with each other. We utilize our approach to study the impact of exposure to metals on child neurodevelopment in Bangladesh and find a nonlinear, interactive relationship between arsenic and manganese. Full Article
sem A semiparametric modeling approach using Bayesian Additive Regression Trees with an application to evaluate heterogeneous treatment effects By projecteuclid.org Published On :: Wed, 16 Oct 2019 22:03 EDT Bret Zeldow, Vincent Lo Re III, Jason Roy. Source: The Annals of Applied Statistics, Volume 13, Number 3, 1989--2010.Abstract: Bayesian Additive Regression Trees (BART) is a flexible machine learning algorithm capable of capturing nonlinearities between an outcome and covariates and interactions among covariates. We extend BART to a semiparametric regression framework in which the conditional expectation of an outcome is a function of treatment, its effect modifiers, and confounders. The confounders are allowed to have unspecified functional form, while treatment and effect modifiers that are directly related to the research question are given a linear form. The result is a Bayesian semiparametric linear regression model where the posterior distribution of the parameters of the linear part can be interpreted as in parametric Bayesian regression. This is useful in situations where a subset of the variables are of substantive interest and the others are nuisance variables that we would like to control for. An example of this occurs in causal modeling with the structural mean model (SMM). Under certain causal assumptions, our method can be used as a Bayesian SMM. Our methods are demonstrated with simulation studies and an application to dataset involving adults with HIV/Hepatitis C coinfection who newly initiate antiretroviral therapy. The methods are available in an R package called semibart. Full Article