egress Robust regression via mutivariate regression depth By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Chao Gao. Source: Bernoulli, Volume 26, Number 2, 1139--1170.Abstract: This paper studies robust regression in the settings of Huber’s $epsilon$-contamination models. We consider estimators that are maximizers of multivariate regression depth functions. These estimators are shown to achieve minimax rates in the settings of $epsilon$-contamination models for various regression problems including nonparametric regression, sparse linear regression, reduced rank regression, etc. We also discuss a general notion of depth function for linear operators that has potential applications in robust functional linear regression. Full Article
egress Multivariate count autoregression By projecteuclid.org Published On :: Tue, 26 Nov 2019 04:00 EST Konstantinos Fokianos, Bård Støve, Dag Tjøstheim, Paul Doukhan. Source: Bernoulli, Volume 26, Number 1, 471--499.Abstract: We are studying linear and log-linear models for multivariate count time series data with Poisson marginals. For studying the properties of such processes we develop a novel conceptual framework which is based on copulas. Earlier contributions impose the copula on the joint distribution of the vector of counts by employing a continuous extension methodology. Instead we introduce a copula function on a vector of associated continuous random variables. This construction avoids conceptual difficulties related to the joint distribution of counts yet it keeps the properties of the Poisson process marginally. Furthermore, this construction can be employed for modeling multivariate count time series with other marginal count distributions. We employ Markov chain theory and the notion of weak dependence to study ergodicity and stationarity of the models we consider. Suitable estimating equations are suggested for estimating unknown model parameters. The large sample properties of the resulting estimators are studied in detail. The work concludes with some simulations and a real data example. Full Article
egress Bayesian Quantile Regression with Mixed Discrete and Nonignorable Missing Covariates By projecteuclid.org Published On :: Thu, 19 Mar 2020 22:02 EDT Zhi-Qiang Wang, Nian-Sheng Tang. Source: Bayesian Analysis, Volume 15, Number 2, 579--604.Abstract: Bayesian inference on quantile regression (QR) model with mixed discrete and non-ignorable missing covariates is conducted by reformulating QR model as a hierarchical structure model. A probit regression model is adopted to specify missing covariate mechanism. A hybrid algorithm combining the Gibbs sampler and the Metropolis-Hastings algorithm is developed to simultaneously produce Bayesian estimates of unknown parameters and latent variables as well as their corresponding standard errors. Bayesian variable selection method is proposed to recognize significant covariates. A Bayesian local influence procedure is presented to assess the effect of minor perturbations to the data, priors and sampling distributions on posterior quantities of interest. Several simulation studies and an example are presented to illustrate the proposed methodologies. Full Article
egress Bayesian Sparse Multivariate Regression with Asymmetric Nonlocal Priors for Microbiome Data Analysis By projecteuclid.org Published On :: Thu, 19 Mar 2020 22:02 EDT Kurtis Shuler, Marilou Sison-Mangus, Juhee Lee. Source: Bayesian Analysis, Volume 15, Number 2, 559--578.Abstract: We propose a Bayesian sparse multivariate regression method to model the relationship between microbe abundance and environmental factors for microbiome data. We model abundance counts of operational taxonomic units (OTUs) with a negative binomial distribution and relate covariates to the counts through regression. Extending conventional nonlocal priors, we construct asymmetric nonlocal priors for regression coefficients to efficiently identify relevant covariates and their effect directions. We build a hierarchical model to facilitate pooling of information across OTUs that produces parsimonious results with improved accuracy. We present simulation studies that compare variable selection performance under the proposed model to those under Bayesian sparse regression models with asymmetric and symmetric local priors and two frequentist models. The simulations show the proposed model identifies important covariates and yields coefficient estimates with favorable accuracy compared with the alternatives. The proposed model is applied to analyze an ocean microbiome dataset collected over time to study the association of harmful algal bloom conditions with microbial communities. Full Article
egress 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
egress 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
egress A Novel Algorithmic Approach to Bayesian Logic Regression (with Discussion) By projecteuclid.org Published On :: Tue, 17 Mar 2020 04:00 EDT Aliaksandr Hubin, Geir Storvik, Florian Frommlet. Source: Bayesian Analysis, Volume 15, Number 1, 263--333.Abstract: Logic regression was developed more than a decade ago as a tool to construct predictors from Boolean combinations of binary covariates. It has been mainly used to model epistatic effects in genetic association studies, which is very appealing due to the intuitive interpretation of logic expressions to describe the interaction between genetic variations. Nevertheless logic regression has (partly due to computational challenges) remained less well known than other approaches to epistatic association mapping. Here we will adapt an advanced evolutionary algorithm called GMJMCMC (Genetically modified Mode Jumping Markov Chain Monte Carlo) to perform Bayesian model selection in the space of logic regression models. After describing the algorithmic details of GMJMCMC we perform a comprehensive simulation study that illustrates its performance given logic regression terms of various complexity. Specifically GMJMCMC is shown to be able to identify three-way and even four-way interactions with relatively large power, a level of complexity which has not been achieved by previous implementations of logic regression. We apply GMJMCMC to reanalyze QTL (quantitative trait locus) mapping data for Recombinant Inbred Lines in Arabidopsis thaliana and from a backcross population in Drosophila where we identify several interesting epistatic effects. The method is implemented in an R package which is available on github. Full Article
egress High-Dimensional Posterior Consistency for Hierarchical Non-Local Priors in Regression By projecteuclid.org Published On :: Mon, 13 Jan 2020 04:00 EST Xuan Cao, Kshitij Khare, Malay Ghosh. Source: Bayesian Analysis, Volume 15, Number 1, 241--262.Abstract: The choice of tuning parameters in Bayesian variable selection is a critical problem in modern statistics. In particular, for Bayesian linear regression with non-local priors, the scale parameter in the non-local prior density is an important tuning parameter which reflects the dispersion of the non-local prior density around zero, and implicitly determines the size of the regression coefficients that will be shrunk to zero. Current approaches treat the scale parameter as given, and suggest choices based on prior coverage/asymptotic considerations. In this paper, we consider the fully Bayesian approach introduced in (Wu, 2016) with the pMOM non-local prior and an appropriate Inverse-Gamma prior on the tuning parameter to analyze the underlying theoretical property. Under standard regularity assumptions, we establish strong model selection consistency in a high-dimensional setting, where $p$ is allowed to increase at a polynomial rate with $n$ or even at a sub-exponential rate with $n$ . Through simulation studies, we demonstrate that our model selection procedure can outperform other Bayesian methods which treat the scale parameter as given, and commonly used penalized likelihood methods, in a range of simulation settings. Full Article
egress 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
egress 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
egress 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
egress 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
egress 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
egress Bayesian Functional Forecasting with Locally-Autoregressive Dependent Processes By projecteuclid.org Published On :: Thu, 19 Dec 2019 22:10 EST Guillaume Kon Kam King, Antonio Canale, Matteo Ruggiero. Source: Bayesian Analysis, Volume 14, Number 4, 1121--1141.Abstract: Motivated by the problem of forecasting demand and offer curves, we introduce a class of nonparametric dynamic models with locally-autoregressive behaviour, and provide a full inferential strategy for forecasting time series of piecewise-constant non-decreasing functions over arbitrary time horizons. The model is induced by a non Markovian system of interacting particles whose evolution is governed by a resampling step and a drift mechanism. The former is based on a global interaction and accounts for the volatility of the functional time series, while the latter is determined by a neighbourhood-based interaction with the past curves and accounts for local trend behaviours, separating these from pure noise. We discuss the implementation of the model for functional forecasting by combining a population Monte Carlo and a semi-automatic learning approach to approximate Bayesian computation which require limited tuning. We validate the inference method with a simulation study, and carry out predictive inference on a real dataset on the Italian natural gas market. Full Article
egress 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
egress 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
egress Fast Model-Fitting of Bayesian Variable Selection Regression Using the Iterative Complex Factorization Algorithm By projecteuclid.org Published On :: Wed, 13 Mar 2019 22:00 EDT Quan Zhou, Yongtao Guan. Source: Bayesian Analysis, Volume 14, Number 2, 573--594.Abstract: Bayesian variable selection regression (BVSR) is able to jointly analyze genome-wide genetic datasets, but the slow computation via Markov chain Monte Carlo (MCMC) hampered its wide-spread usage. Here we present a novel iterative method to solve a special class of linear systems, which can increase the speed of the BVSR model-fitting tenfold. The iterative method hinges on the complex factorization of the sum of two matrices and the solution path resides in the complex domain (instead of the real domain). Compared to the Gauss-Seidel method, the complex factorization converges almost instantaneously and its error is several magnitude smaller than that of the Gauss-Seidel method. More importantly, the error is always within the pre-specified precision while the Gauss-Seidel method is not. For large problems with thousands of covariates, the complex factorization is 10–100 times faster than either the Gauss-Seidel method or the direct method via the Cholesky decomposition. In BVSR, one needs to repetitively solve large penalized regression systems whose design matrices only change slightly between adjacent MCMC steps. This slight change in design matrix enables the adaptation of the iterative complex factorization method. The computational innovation will facilitate the wide-spread use of BVSR in reanalyzing genome-wide association datasets. Full Article
egress 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
egress 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
egress Models as Approximations II: A Model-Free Theory of Parametric Regression By projecteuclid.org Published On :: Wed, 08 Jan 2020 04:00 EST Andreas Buja, Lawrence Brown, Arun Kumar Kuchibhotla, Richard Berk, Edward George, Linda Zhao. Source: Statistical Science, Volume 34, Number 4, 545--565.Abstract: We develop a model-free theory of general types of parametric regression for i.i.d. observations. The theory replaces the parameters of parametric models with statistical functionals, to be called “regression functionals,” defined on large nonparametric classes of joint ${x extrm{-}y}$ distributions, without assuming a correct model. Parametric models are reduced to heuristics to suggest plausible objective functions. An example of a regression functional is the vector of slopes of linear equations fitted by OLS to largely arbitrary ${x extrm{-}y}$ distributions, without assuming a linear model (see Part I). More generally, regression functionals can be defined by minimizing objective functions, solving estimating equations, or with ad hoc constructions. In this framework, it is possible to achieve the following: (1) define a notion of “well-specification” for regression functionals that replaces the notion of correct specification of models, (2) propose a well-specification diagnostic for regression functionals based on reweighting distributions and data, (3) decompose sampling variability of regression functionals into two sources, one due to the conditional response distribution and another due to the regressor distribution interacting with misspecification, both of order $N^{-1/2}$, (4) exhibit plug-in/sandwich estimators of standard error as limit cases of ${x extrm{-}y}$ bootstrap estimators, and (5) provide theoretical heuristics to indicate that ${x extrm{-}y}$ bootstrap standard errors may generally be preferred over sandwich estimators. Full Article
egress 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
egress 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
egress 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
egress Angola's Choice: Reform or Regress By feedproxy.google.com Published On :: Sun, 06 Apr 2003 22:00:00 GMT Full Article
egress How to run a regressive test and merge the ncsim.trn file of all test into a single file to view the waveform in simvision ? By feedproxy.google.com Published On :: Mon, 13 Jan 2020 12:04:01 GMT Hi all, I want to know how to run a regressive test in cadence and merge all ncsim .trn file of each test case into a single file to view all waveform in simvision. I am using Makefile to invoke the test case. eg:- test0: irun -uvm -sv -access +rwc $(RTL) $(INTER) $(PKG) $(TOP) $(probe) +UVM_VERBOSITY=UVM_MEDIUM +UVM_TESTNAME=test0 test1: irun -uvm -sv -access +rwc $(RTL) $(INTER) $(PKG) $(TOP) $(probe) +UVM_VERBOSITY=UVM_MEDIUM +UVM_TESTNAME=test1 I just to call test0 followed by test1 or parallel both test and view the waveform for both tests case. I new to this tool and help me with it Full Article
egress Pharmacologic Inhibitor of DNA-PK, M3814, Potentiates Radiotherapy and Regresses Human Tumors in Mouse Models By mct.aacrjournals.org Published On :: 2020-05-04T05:39:42-07:00 Physical and chemical DNA-damaging agents are used widely in the treatment of cancer. Double-strand break (DSB) lesions in DNA are the most deleterious form of damage and, if left unrepaired, can effectively kill cancer cells. DNA-dependent protein kinase (DNA-PK) is a critical component of nonhomologous end joining (NHEJ), one of the two major pathways for DSB repair. Although DNA-PK has been considered an attractive target for cancer therapy, the development of pharmacologic DNA-PK inhibitors for clinical use has been lagging. Here, we report the discovery and characterization of a potent, selective, and orally bioavailable DNA-PK inhibitor, M3814 (peposertib), and provide in vivo proof of principle for DNA-PK inhibition as a novel approach to combination radiotherapy. M3814 potently inhibits DNA-PK catalytic activity and sensitizes multiple cancer cell lines to ionizing radiation (IR) and DSB-inducing agents. Inhibition of DNA-PK autophosphorylation in cancer cells or xenograft tumors led to an increased number of persistent DSBs. Oral administration of M3814 to two xenograft models of human cancer, using a clinically established 6-week fractionated radiation schedule, strongly potentiated the antitumor activity of IR and led to complete tumor regression at nontoxic doses. Our results strongly support DNA-PK inhibition as a novel approach for the combination radiotherapy of cancer. M3814 is currently under investigation in combination with radiotherapy in clinical trials. Full Article
egress Deciphering Sex-Specific Genetic Architectures Using Local Bayesian Regressions [Genetics of Complex Traits] By www.genetics.org Published On :: 2020-05-05T06:43:41-07:00 Many complex human traits exhibit differences between sexes. While numerous factors likely contribute to this phenomenon, growing evidence from genome-wide studies suggest a partial explanation: that males and females from the same population possess differing genetic architectures. Despite this, mapping gene-by-sex (GxS) interactions remains a challenge likely because the magnitude of such an interaction is typically and exceedingly small; traditional genome-wide association techniques may be underpowered to detect such events, due partly to the burden of multiple test correction. Here, we developed a local Bayesian regression (LBR) method to estimate sex-specific SNP marker effects after fully accounting for local linkage-disequilibrium (LD) patterns. This enabled us to infer sex-specific effects and GxS interactions either at the single SNP level, or by aggregating the effects of multiple SNPs to make inferences at the level of small LD-based regions. Using simulations in which there was imperfect LD between SNPs and causal variants, we showed that aggregating sex-specific marker effects with LBR provides improved power and resolution to detect GxS interactions over traditional single-SNP-based tests. When using LBR to analyze traits from the UK Biobank, we detected a relatively large GxS interaction impacting bone mineral density within ABO, and replicated many previously detected large-magnitude GxS interactions impacting waist-to-hip ratio. We also discovered many new GxS interactions impacting such traits as height and body mass index (BMI) within regions of the genome where both male- and female-specific effects explain a small proportion of phenotypic variance (R2 < 1 x 10–4), but are enriched in known expression quantitative trait loci. Full Article
egress Groundwater recharge susceptibility mapping using logistic regression model and bivariate statistical analysis By qjegh.lyellcollection.org Published On :: 2020-05-01T00:46:18-07:00 A logistic regression model and a bivariate statistical analysis were used in this paper to evaluate the groundwater recharge susceptibility. The approach is based on the assessment of the relationship involving groundwater recharge and parameters that influence this hydrological process. Surface parameters and aquifer-related parameters were evaluated as thematic map layers using ArcGIS. Then, a weighted-rating method was adopted to categorize each parameter's map. To assess the role of each parameter in the aquifer recharge, a logistic regression model and a bivariate statistical analysis were applied to the Guenniche phreatic aquifer (Tunisia). Models are explored to establish a map showing the aquifer recharge susceptibility. The code Modflow was used to simulate the consequence of the recharge. The recharge amount was introduced in the model and was tested to verify the recharge effect on the hydraulic head for the two models. The obtained results reveal that the recharge as mapped in the bivariate statistical model has a minor impact on the hydraulic head. Results of the logistic regression model are more significant as the hydraulic head is widely affected. This model provides good results in mapping the spatial distribution of the aquifer recharge susceptibility. Full Article
egress Whole-Cell Phenotypic Screening of Medicines for Malaria Venture Pathogen Box Identifies Specific Inhibitors of Plasmodium falciparum Late-Stage Development and Egress [Experimental Therapeutics] By aac.asm.org Published On :: 2020-04-21T08:01:09-07:00 We report a systematic, cellular phenotype-based antimalarial screening of the Medicines for Malaria Venture Pathogen Box collection, which facilitated the identification of specific blockers of late-stage intraerythrocytic development of Plasmodium falciparum. First, from standard growth inhibition assays, we identified 173 molecules with antimalarial activity (50% effective concentration [EC50] ≤ 10 μM), which included 62 additional molecules over previously known antimalarial candidates from the Pathogen Box. We identified 90 molecules with EC50 of ≤1 μM, which had significant effect on the ring-trophozoite transition, while 9 molecules inhibited the trophozoite-schizont transition and 21 molecules inhibited the schizont-ring transition (with ≥50% parasites failing to proceed to the next stage) at 1 μM. We therefore rescreened all 173 molecules and validated hits in microscopy to prioritize 12 hits as selective blockers of the schizont-ring transition. Seven of these molecules inhibited the calcium ionophore-induced egress of Toxoplasma gondii, a related apicomplexan parasite, suggesting that the inhibitors may be acting via a conserved mechanism which could be further exploited for target identification studies. We demonstrate that two molecules, MMV020670 and MMV026356, identified as schizont inhibitors in our screens, induce the fragmentation of DNA in merozoites, thereby impairing their ability to egress and invade. Further mechanistic studies would facilitate the therapeutic exploitation of these molecules as broadly active inhibitors targeting late-stage development and egress of apicomplexan parasites relevant to human health. Full Article
egress We must not regress in the next leg of lockdown By www.mid-day.com Published On :: 4 May 2020 01:30:38 GMT Our lives are still in lockdown as the next phase begins today. There is still some confusion as people are puzzled about zones — containment, red, green, orange or whatever. There should be greater clarity soon, but one thing is certain in the city, that we are continuing to see curbs and restrictions as efforts are on to flatten this curve. Today, Maharashtra stands at the unenviable No. 1 spot in Coronavirus cases, so one expects that clamps will still be extremely strict in this state.So, as we head into the next phase of the lockdown, let us realise that the onus is on us, as equal and important partners in attempts to flatten the curve in the state. Be as disciplined as possible within the new parameters set for us. Adhere to new rules, where there is a grey area, obey the cops if they call you out on certain matters, instead of arguing endlessly about this zone or that, about this rule or the other. Remember that every arm of the city is stretched to breaking point, so it is wiser not to try someone's patience with unnecessary arguments. There can be no let-up when it comes to social distancing or wearing masks. These two aspects, in fact, seem to be the bulwark of our fight against the virus, so we need to be even more aware and obedient when it comes to adhering to this. The city, divided into different zones, is throwing up unique challenges. It is on us to see that we do not regress to earlier phases but move ahead — slowly if need be — towards more ease, more mobility. This is a struggle for a different kind of freedom and we all are fighters in it. Catch up on all the latest Mumbai news, crime news, current affairs, and a complete guide from food to things to do and events across Mumbai. Also download the new mid-day Android and iOS apps to get latest updates. Mid-Day is now on Telegram. Click here to join our channel (@middayinfomedialtd) and stay updated with the latest news Full Article
egress How to handle sleep regression in kids due to the pandemic, according to sleep expert Harvey Karp By www.businessinsider.in Published On :: 9 May 2020, 00:29 Due to schedule disruptions, stress, and being stuck inside, many babies and children are experiencing sleep regression amid the coronavirus pandemic.Dr. Harvey Karp, a pediatrician and sleep expert who created the SNOO crib, shares some tips on how parents can effectively address sleep regression.Karp recommends a consistent bedtime routine, spending time outdoors, and engaging in soothing talk before bed.Visit Insider's homepage for more stories.If your child's sleep has become more erratic during the coronavirus crisis, know that you're not alone. In fact, Italian pediatricians reported widespread sleep disturbances among their young patients as the pandemic hit its peak there.Between our new home-bound lives and the stress of a global pandemic, many factors can compromise our kids' sleep Full Article
egress Rebecca Long-Bailey's clashes with aide over her 'regressive' abortion views By www.dailymail.co.uk Published On :: Sun, 19 Jan 2020 02:03:51 GMT In a defiant riposte, she hinted that her concerns had been 'misrepresented' in a bid to damage her bid to succeed Jeremy Corbyn. Full Article
egress Water quality index prediction using multiple linear fuzzy regression model: case study in Perak River, Malaysia / Samsul Ariffin Abdul Karim, Nur Fatonah Kamsani By library.mit.edu Published On :: Sun, 29 Mar 2020 06:19:37 EDT Online Resource Full Article
egress A second course in statistics : regression analysis / William Mendenhall, Terry Sincich By prospero.murdoch.edu.au Published On :: Mendenhall, William, author Full Article
egress Robust nonlinear regression : with application using R / Hossein Riazoshams (Lamerd Islamic Azad University, Iran, Stockholm University, Sweden, University of Putra, Malaysia), Habshah Midi (University of Putra, Malaysia), Gebrenegus Ghilagaber (Stockholm By prospero.murdoch.edu.au Published On :: Riazoshams, Hossein, 1971- author Full Article
egress [ASAP] Complete Regression of Carcinoma via Combined C-RAF and EGFR Targeted Therapy By feedproxy.google.com Published On :: Tue, 14 Apr 2020 04:00:00 GMT ACS Medicinal Chemistry LettersDOI: 10.1021/acsmedchemlett.0c00159 Full Article
egress Linear regression : a mathematical introduction / Damodar N. Gujarati (Professor Emeritus of Economics, U.S. Military Academy, West Point, NY) By prospero.murdoch.edu.au Published On :: Gujarati, Damodar N., author Full Article
egress Flexible Bayesian regression modelling / edited by Yanan Fan, David Nott, Mike S. Smith, Jean-Luc Dortet-Bernadet By library.mit.edu Published On :: Sun, 5 Apr 2020 06:19:51 EDT Dewey Library - QA278.2.F53 2020 Full Article
egress Quantile regression for cross-sectional and time series data: applications in energy markets using R / Jorge M. Uribe, Montserrat Guillen By library.mit.edu Published On :: Sun, 3 May 2020 07:23:24 EDT Online Resource Full Article
egress Learning Regression Analysis by Simulation [electronic resource] / by Kunio Takezawa By darius.uleth.ca Published On :: Tokyo : Springer Japan : Imprint: Springer, 2014 Full Article
egress Symbolic regression of thermophysical model using genetic programming By digital.lib.usf.edu Published On :: Sat, 15 Feb 2014 18:12:00 -0400 Full Article
egress Lake stage fluctuation study in West-Central Florida using multiple regression models By digital.lib.usf.edu Published On :: Sat, 15 Feb 2014 18:16:27 -0400 Full Article
egress Regression approach to software reliability models By digital.lib.usf.edu Published On :: Sat, 15 Feb 2014 18:32:24 -0400 Full Article
egress Advancements in rapid load test data regression By digital.lib.usf.edu Published On :: Sat, 15 Feb 2014 18:39:09 -0400 Full Article
egress Motichoor Chaknachoor movie review: Astonishingly regressive By indianexpress.com Published On :: Thu, 14 Nov 2019 16:48:44 +0000 Full Article Entertainment Movie Review
egress Letter to the Editor: Regressive tax By indianexpress.com Published On :: Tue, 06 Feb 2018 18:53:59 +0000 Full Article Letters to Editor Opinion