qua Duties and qualifications of physicians, an introductory lecture / by John Ware. By feedproxy.google.com Published On :: Oxford : J.H. Parker, 1849. Full Article
qua Elements of anatomy / Jones Quain. By feedproxy.google.com Published On :: London : Longmans, Green, 1882. Full Article
qua Elements of anatomy / Jones Quain. By feedproxy.google.com Published On :: London : Walton and Maberly, 1864-67. Full Article
qua Elements of anatomy / Jones Quain. By feedproxy.google.com Published On :: London : Longmans, Green, 1890-96. Full Article
qua Elements of anatomy / Jones Quain. By feedproxy.google.com Published On :: London : Longmans, Green, 1898. Full Article
qua Elements of anatomy / Jones Quain. By feedproxy.google.com Published On :: London : Longmans, Green, 1898. Full Article
qua Elements of anatomy / Jones Quain. By feedproxy.google.com Published On :: London : Longmans, Green, 1876. Full Article
qua Essai de pneumatologie médicale : recherches physiologiques, cliniques et thérapeutiques sur les gaz / par J.-N. Demarquay. By feedproxy.google.com Published On :: Londres : Paris, 1866. Full Article
qua Mississippi Ranks 47th on Quality Counts Annual Report Card By feedproxy.google.com Published On :: Tue, 03 Sep 2019 00:00:00 +0000 The state, which earned a D-plus, scored low on the Chance for Success Index, which tracks a host of socioeconomic factors that can affect the educational environment. Full Article Mississippi
qua Rediscovering School Quality Reviews By feedproxy.google.com Published On :: Wed, 07 Mar 2018 00:00:00 +0000 Resurrecting an old idea about assessing school quality could allow schools to examine a broad range of data on performance and practices and lead to improvement. Full Article Vermont
qua Earthquake Scuttles Classes in Alaska, As California Students Return to School By feedproxy.google.com Published On :: Tue, 11 Dec 2018 00:00:00 +0000 While thousands of students in wildfire-ravaged Northern California resumed classes last week, thousands of others in Alaska stayed home after a 7.0 magnitude earthquake struck Nov. 30. Full Article Alaska
qua Observationes et historiae omnes & singulae è Guiljelmi Harvei libello De generatione animalium excerptae ... : Item Wilhelmi Langly De generatione animalium observationes quaedam. Accedunt Ovi faecundi singulis ab incubatione diebus factae inspe By feedproxy.google.com Published On :: Amstelodami : Typis A. Wolfgang, 1674. Full Article
qua Les oeuures du R. P. Gabriel de Castaigne, tant medicinales que chymiques, : diuisées en quatre principaux traitez. I. Le paradis terrestre. II. Le grand miracle de la nature metallique. III. L'or potable. IV. Le thresor philosophique de la medec By feedproxy.google.com Published On :: A Paris : Chez Iean Dhourry, au bout du Pont-Neuf, près les Augustins, à l'Image S. Iean, M. DC. LXI. [1661] Full Article
qua A young woman and a young man in the reign of King Charles II having a quarrel: they prepare to surrender each other's portrait miniature. Engraving by C. Heath, 1824, after G.S. Newton. By feedproxy.google.com Published On :: London (6 Seymour Place, Euston Square) : Charles Heath ; [London] (Poultry) : Robert Jennings, May 15 1827 ([London] : Printed by McQueen) Full Article
qua Lachlan Macquarie land grant to John Laurie By feedproxy.google.com Published On :: 2/10/2015 12:00:00 AM Full Article
qua Nonparametric confidence intervals for conditional quantiles with large-dimensional covariates By projecteuclid.org Published On :: Tue, 05 May 2020 22:00 EDT Laurent Gardes. Source: Electronic Journal of Statistics, Volume 14, Number 1, 661--701.Abstract: The first part of the paper is dedicated to the construction of a $gamma$ - nonparametric confidence interval for a conditional quantile with a level depending on the sample size. When this level tends to 0 or 1 as the sample size increases, the conditional quantile is said to be extreme and is located in the tail of the conditional distribution. The proposed confidence interval is constructed by approximating the distribution of the order statistics selected with a nearest neighbor approach by a Beta distribution. We show that its coverage probability converges to the preselected probability $gamma $ and its accuracy is illustrated on a simulation study. When the dimension of the covariate increases, the coverage probability of the confidence interval can be very different from $gamma $. This is a well known consequence of the data sparsity especially in the tail of the distribution. In a second part, a dimension reduction procedure is proposed in order to select more appropriate nearest neighbors in the right tail of the distribution and in turn to obtain a better coverage probability for extreme conditional quantiles. This procedure is based on the Tail Conditional Independence assumption introduced in (Gardes, Extremes , pp. 57–95, 18(3) , 2018). Full Article
qua Parseval inequalities and lower bounds for variance-based sensitivity indices By projecteuclid.org Published On :: Tue, 05 May 2020 22:00 EDT Olivier Roustant, Fabrice Gamboa, Bertrand Iooss. Source: Electronic Journal of Statistics, Volume 14, Number 1, 386--412.Abstract: The so-called polynomial chaos expansion is widely used in computer experiments. For example, it is a powerful tool to estimate Sobol’ sensitivity indices. In this paper, we consider generalized chaos expansions built on general tensor Hilbert basis. In this frame, we revisit the computation of the Sobol’ indices with Parseval equalities and give general lower bounds for these indices obtained by truncation. The case of the eigenfunctions system associated with a Poincaré differential operator leads to lower bounds involving the derivatives of the analyzed function and provides an efficient tool for variable screening. These lower bounds are put in action both on toy and real life models demonstrating their accuracy. Full Article
qua Monotone least squares and isotonic quantiles By projecteuclid.org Published On :: Wed, 22 Apr 2020 04:02 EDT Alexandre Mösching, Lutz Dümbgen. Source: Electronic Journal of Statistics, Volume 14, Number 1, 24--49.Abstract: We consider bivariate observations $(X_{1},Y_{1}),ldots,(X_{n},Y_{n})$ such that, conditional on the $X_{i}$, the $Y_{i}$ are independent random variables. Precisely, the conditional distribution function of $Y_{i}$ equals $F_{X_{i}}$, where $(F_{x})_{x}$ is an unknown family of distribution functions. Under the sole assumption that $xmapsto F_{x}$ is isotonic with respect to stochastic order, one can estimate $(F_{x})_{x}$ in two ways: (i) For any fixed $y$ one estimates the antitonic function $xmapsto F_{x}(y)$ via nonparametric monotone least squares, replacing the responses $Y_{i}$ with the indicators $1_{[Y_{i}le y]}$. (ii) For any fixed $eta in (0,1)$ one estimates the isotonic quantile function $xmapsto F_{x}^{-1}(eta)$ via a nonparametric version of regression quantiles. We show that these two approaches are closely related, with (i) being more flexible than (ii). Then, under mild regularity conditions, we establish rates of convergence for the resulting estimators $hat{F}_{x}(y)$ and $hat{F}_{x}^{-1}(eta)$, uniformly over $(x,y)$ and $(x,eta)$ in certain rectangles as well as uniformly in $y$ or $eta$ for a fixed $x$. Full Article
qua Random distributions via Sequential Quantile Array By projecteuclid.org Published On :: Wed, 08 Apr 2020 22:01 EDT Annalisa Fabretti, Samantha Leorato. Source: Electronic Journal of Statistics, Volume 14, Number 1, 1611--1647.Abstract: We propose a method to generate random distributions with known quantile distribution, or, more generally, with known distribution for some form of generalized quantile. The method takes inspiration from the random Sequential Barycenter Array distributions (SBA) proposed by Hill and Monticino (1998) which generates a Random Probability Measure (RPM) with known expected value. We define the Sequential Quantile Array (SQA) and show how to generate a random SQA from which we can derive RPMs. The distribution of the generated SQA-RPM can have full support and the RPMs can be both discrete, continuous and differentiable. We face also the problem of the efficient implementation of the procedure that ensures that the approximation of the SQA-RPM by a finite number of steps stays close to the SQA-RPM obtained theoretically by the procedure. Finally, we compare SQA-RPMs with similar approaches as Polya Tree. Full Article
qua A general drift estimation procedure for stochastic differential equations with additive fractional noise By projecteuclid.org Published On :: Tue, 25 Feb 2020 22:00 EST Fabien Panloup, Samy Tindel, Maylis Varvenne. Source: Electronic Journal of Statistics, Volume 14, Number 1, 1075--1136.Abstract: In this paper we consider the drift estimation problem for a general differential equation driven by an additive multidimensional fractional Brownian motion, under ergodic assumptions on the drift coefficient. Our estimation procedure is based on the identification of the invariant measure, and we provide consistency results as well as some information about the convergence rate. We also give some examples of coefficients for which the identifiability assumption for the invariant measure is satisfied. Full Article
qua 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
qua Derivative-Free Methods for Policy Optimization: Guarantees for Linear Quadratic Systems By Published On :: 2020 We study derivative-free methods for policy optimization over the class of linear policies. We focus on characterizing the convergence rate of these methods when applied to linear-quadratic systems, and study various settings of driving noise and reward feedback. Our main theoretical result provides an explicit bound on the sample or evaluation complexity: we show that these methods are guaranteed to converge to within any pre-specified tolerance of the optimal policy with a number of zero-order evaluations that is an explicit polynomial of the error tolerance, dimension, and curvature properties of the problem. Our analysis reveals some interesting differences between the settings of additive driving noise and random initialization, as well as the settings of one-point and two-point reward feedback. Our theory is corroborated by simulations of derivative-free methods in application to these systems. Along the way, we derive convergence rates for stochastic zero-order optimization algorithms when applied to a certain class of non-convex problems. Full Article
qua Latent Simplex Position Model: High Dimensional Multi-view Clustering with Uncertainty Quantification By Published On :: 2020 High dimensional data often contain multiple facets, and several clustering patterns can co-exist under different variable subspaces, also known as the views. While multi-view clustering algorithms were proposed, the uncertainty quantification remains difficult --- a particular challenge is in the high complexity of estimating the cluster assignment probability under each view, and sharing information among views. In this article, we propose an approximate Bayes approach --- treating the similarity matrices generated over the views as rough first-stage estimates for the co-assignment probabilities; in its Kullback-Leibler neighborhood, we obtain a refined low-rank matrix, formed by the pairwise product of simplex coordinates. Interestingly, each simplex coordinate directly encodes the cluster assignment uncertainty. For multi-view clustering, we let each view draw a parameterization from a few candidates, leading to dimension reduction. With high model flexibility, the estimation can be efficiently carried out as a continuous optimization problem, hence enjoys gradient-based computation. The theory establishes the connection of this model to a random partition distribution under multiple views. Compared to single-view clustering approaches, substantially more interpretable results are obtained when clustering brains from a human traumatic brain injury study, using high-dimensional gene expression data. Full Article
qua $W^{1,p}$-Solutions of the transport equation by stochastic perturbation By projecteuclid.org Published On :: Mon, 03 Feb 2020 04:00 EST David A. C. Mollinedo. Source: Brazilian Journal of Probability and Statistics, Volume 34, Number 1, 188--201.Abstract: We consider the stochastic transport equation with a possibly unbounded Hölder continuous vector field. Well-posedness is proved, namely, we show existence, uniqueness and strong stability of $W^{1,p}$-weak solutions. Full Article
qua Density for solutions to stochastic differential equations with unbounded drift By projecteuclid.org Published On :: Mon, 10 Jun 2019 04:04 EDT Christian Olivera, Ciprian Tudor. Source: Brazilian Journal of Probability and Statistics, Volume 33, Number 3, 520--531.Abstract: Via a special transform and by using the techniques of the Malliavin calculus, we analyze the density of the solution to a stochastic differential equation with unbounded drift. Full Article
qua Fractional backward stochastic variational inequalities with non-Lipschitz coefficient By projecteuclid.org Published On :: Mon, 10 Jun 2019 04:04 EDT Katarzyna Jańczak-Borkowska. Source: Brazilian Journal of Probability and Statistics, Volume 33, Number 3, 480--497.Abstract: We prove the existence and uniqueness of the solution of backward stochastic variational inequalities with respect to fractional Brownian motion and with non-Lipschitz coefficient. We assume that $H>1/2$. Full Article
qua Learned Step Size Quantization. (arXiv:1902.08153v3 [cs.LG] UPDATED) By arxiv.org Published On :: Deep networks run with low precision operations at inference time offer power and space advantages over high precision alternatives, but need to overcome the challenge of maintaining high accuracy as precision decreases. Here, we present a method for training such networks, Learned Step Size Quantization, that achieves the highest accuracy to date on the ImageNet dataset when using models, from a variety of architectures, with weights and activations quantized to 2-, 3- or 4-bits of precision, and that can train 3-bit models that reach full precision baseline accuracy. Our approach builds upon existing methods for learning weights in quantized networks by improving how the quantizer itself is configured. Specifically, we introduce a novel means to estimate and scale the task loss gradient at each weight and activation layer's quantizer step size, such that it can be learned in conjunction with other network parameters. This approach works using different levels of precision as needed for a given system and requires only a simple modification of existing training code. Full Article
qua Physics-informed neural network for ultrasound nondestructive quantification of surface breaking cracks. (arXiv:2005.03596v1 [cs.LG]) By arxiv.org Published On :: We introduce an optimized physics-informed neural network (PINN) trained to solve the problem of identifying and characterizing a surface breaking crack in a metal plate. PINNs are neural networks that can combine data and physics in the learning process by adding the residuals of a system of Partial Differential Equations to the loss function. Our PINN is supervised with realistic ultrasonic surface acoustic wave data acquired at a frequency of 5 MHz. The ultrasonic surface wave data is represented as a surface deformation on the top surface of a metal plate, measured by using the method of laser vibrometry. The PINN is physically informed by the acoustic wave equation and its convergence is sped up using adaptive activation functions. The adaptive activation function uses a scalable hyperparameter in the activation function, which is optimized to achieve best performance of the network as it changes dynamically the topology of the loss function involved in the optimization process. The usage of adaptive activation function significantly improves the convergence, notably observed in the current study. We use PINNs to estimate the speed of sound of the metal plate, which we do with an error of 1\%, and then, by allowing the speed of sound to be space dependent, we identify and characterize the crack as the positions where the speed of sound has decreased. Our study also shows the effect of sub-sampling of the data on the sensitivity of sound speed estimates. More broadly, the resulting model shows a promising deep neural network model for ill-posed inverse problems. Full Article
qua CARL: Controllable Agent with Reinforcement Learning for Quadruped Locomotion. (arXiv:2005.03288v1 [cs.LG]) By arxiv.org Published On :: Motion synthesis in a dynamic environment has been a long-standing problem for character animation. Methods using motion capture data tend to scale poorly in complex environments because of their larger capturing and labeling requirement. Physics-based controllers are effective in this regard, albeit less controllable. In this paper, we present CARL, a quadruped agent that can be controlled with high-level directives and react naturally to dynamic environments. Starting with an agent that can imitate individual animation clips, we use Generative Adversarial Networks to adapt high-level controls, such as speed and heading, to action distributions that correspond to the original animations. Further fine-tuning through the deep reinforcement learning enables the agent to recover from unseen external perturbations while producing smooth transitions. It then becomes straightforward to create autonomous agents in dynamic environments by adding navigation modules over the entire process. We evaluate our approach by measuring the agent's ability to follow user control and provide a visual analysis of the generated motion to show its effectiveness. Full Article
qua 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
qua Machine learning in aquaculture : hunger classification of Lates calcarifer By dal.novanet.ca Published On :: Fri, 1 May 2020 19:44:43 -0300 Author: Mohd Razman, Mohd Azraai, authorCallnumber: OnlineISBN: 9789811522376 (electronic bk.) Full Article
qua Drying atlas : drying kinetics and quality of agricultural products By dal.novanet.ca Published On :: Fri, 1 May 2020 19:44:43 -0300 Author: Mühlbauer, Werner, authorCallnumber: OnlineISBN: 9780128181638 (electronic bk.) Full Article
qua Crafting qualitative research : beyond positivist traditions By dal.novanet.ca Published On :: Fri, 1 May 2020 19:44:43 -0300 Author: Prasad, Pushkala, author.Callnumber: OnlineISBN: 9781315715070 (e-book) Full Article
qua Aquatic biopolymers : understanding their industrial significance and environmental implications By dal.novanet.ca Published On :: Fri, 1 May 2020 19:44:43 -0300 Author: Olatunji, Ololade.Callnumber: OnlineISBN: 9783030347093 (electronic bk.) Full Article
qua Penalized generalized empirical likelihood with a diverging number of general estimating equations for censored data By projecteuclid.org Published On :: Mon, 17 Feb 2020 04:02 EST Niansheng Tang, Xiaodong Yan, Xingqiu Zhao. Source: The Annals of Statistics, Volume 48, Number 1, 607--627.Abstract: This article considers simultaneous variable selection and parameter estimation as well as hypothesis testing in censored survival models where a parametric likelihood is not available. For the problem, we utilize certain growing dimensional general estimating equations and propose a penalized generalized empirical likelihood, where the general estimating equations are constructed based on the semiparametric efficiency bound of estimation with given moment conditions. The proposed penalized generalized empirical likelihood estimators enjoy the oracle properties, and the estimator of any fixed dimensional vector of nonzero parameters achieves the semiparametric efficiency bound asymptotically. Furthermore, we show that the penalized generalized empirical likelihood ratio test statistic has an asymptotic central chi-square distribution. The conditions of local and restricted global optimality of weighted penalized generalized empirical likelihood estimators are also discussed. We present a two-layer iterative algorithm for efficient implementation, and investigate its convergence property. The performance of the proposed methods is demonstrated by extensive simulation studies, and a real data example is provided for illustration. Full Article
qua Envelope-based sparse partial least squares By projecteuclid.org Published On :: Mon, 17 Feb 2020 04:02 EST Guangyu Zhu, Zhihua Su. Source: The Annals of Statistics, Volume 48, Number 1, 161--182.Abstract: Sparse partial least squares (SPLS) is widely used in applied sciences as a method that performs dimension reduction and variable selection simultaneously in linear regression. Several implementations of SPLS have been derived, among which the SPLS proposed in Chun and Keleş ( J. R. Stat. Soc. Ser. B. Stat. Methodol. 72 (2010) 3–25) is very popular and highly cited. However, for all of these implementations, the theoretical properties of SPLS are largely unknown. In this paper, we propose a new version of SPLS, called the envelope-based SPLS, using a connection between envelope models and partial least squares (PLS). We establish the consistency, oracle property and asymptotic normality of the envelope-based SPLS estimator. The large-sample scenario and high-dimensional scenario are both considered. We also develop the envelope-based SPLS estimators under the context of generalized linear models, and discuss its theoretical properties including consistency, oracle property and asymptotic distribution. Numerical experiments and examples show that the envelope-based SPLS estimator has better variable selection and prediction performance over the SPLS estimator ( J. R. Stat. Soc. Ser. B. Stat. Methodol. 72 (2010) 3–25). Full Article
qua Quantile regression under memory constraint By projecteuclid.org Published On :: Wed, 30 Oct 2019 22:03 EDT Xi Chen, Weidong Liu, Yichen Zhang. Source: The Annals of Statistics, Volume 47, Number 6, 3244--3273.Abstract: This paper studies the inference problem in quantile regression (QR) for a large sample size $n$ but under a limited memory constraint, where the memory can only store a small batch of data of size $m$. A natural method is the naive divide-and-conquer approach, which splits data into batches of size $m$, computes the local QR estimator for each batch and then aggregates the estimators via averaging. However, this method only works when $n=o(m^{2})$ and is computationally expensive. This paper proposes a computationally efficient method, which only requires an initial QR estimator on a small batch of data and then successively refines the estimator via multiple rounds of aggregations. Theoretically, as long as $n$ grows polynomially in $m$, we establish the asymptotic normality for the obtained estimator and show that our estimator with only a few rounds of aggregations achieves the same efficiency as the QR estimator computed on all the data. Moreover, our result allows the case that the dimensionality $p$ goes to infinity. The proposed method can also be applied to address the QR problem under distributed computing environment (e.g., in a large-scale sensor network) or for real-time streaming data. Full Article
qua On testing conditional qualitative treatment effects By projecteuclid.org Published On :: Tue, 21 May 2019 04:00 EDT Chengchun Shi, Rui Song, Wenbin Lu. Source: The Annals of Statistics, Volume 47, Number 4, 2348--2377.Abstract: Precision medicine is an emerging medical paradigm that focuses on finding the most effective treatment strategy tailored for individual patients. In the literature, most of the existing works focused on estimating the optimal treatment regime. However, there has been less attention devoted to hypothesis testing regarding the optimal treatment regime. In this paper, we first introduce the notion of conditional qualitative treatment effects (CQTE) of a set of variables given another set of variables and provide a class of equivalent representations for the null hypothesis of no CQTE. The proposed definition of CQTE does not assume any parametric form for the optimal treatment rule and plays an important role for assessing the incremental value of a set of new variables in optimal treatment decision making conditional on an existing set of prescriptive variables. We then propose novel testing procedures for no CQTE based on kernel estimation of the conditional contrast functions. We show that our test statistics have asymptotically correct size and nonnegligible power against some nonstandard local alternatives. The empirical performance of the proposed tests are evaluated by simulations and an application to an AIDS data set. Full Article
qua Convergence rates of least squares regression estimators with heavy-tailed errors By projecteuclid.org Published On :: Tue, 21 May 2019 04:00 EDT Qiyang Han, Jon A. Wellner. Source: The Annals of Statistics, Volume 47, Number 4, 2286--2319.Abstract: We study the performance of the least squares estimator (LSE) in a general nonparametric regression model, when the errors are independent of the covariates but may only have a $p$th moment ($pgeq1$). In such a heavy-tailed regression setting, we show that if the model satisfies a standard “entropy condition” with exponent $alphain(0,2)$, then the $L_{2}$ loss of the LSE converges at a rate [mathcal{O}_{mathbf{P}}igl(n^{-frac{1}{2+alpha}}vee n^{-frac{1}{2}+frac{1}{2p}}igr).] Such a rate cannot be improved under the entropy condition alone. This rate quantifies both some positive and negative aspects of the LSE in a heavy-tailed regression setting. On the positive side, as long as the errors have $pgeq1+2/alpha$ moments, the $L_{2}$ loss of the LSE converges at the same rate as if the errors are Gaussian. On the negative side, if $p<1+2/alpha$, there are (many) hard models at any entropy level $alpha$ for which the $L_{2}$ loss of the LSE converges at a strictly slower rate than other robust estimators. The validity of the above rate relies crucially on the independence of the covariates and the errors. In fact, the $L_{2}$ loss of the LSE can converge arbitrarily slowly when the independence fails. The key technical ingredient is a new multiplier inequality that gives sharp bounds for the “multiplier empirical process” associated with the LSE. We further give an application to the sparse linear regression model with heavy-tailed covariates and errors to demonstrate the scope of this new inequality. Full Article
qua Modifying the Chi-square and the CMH test for population genetic inference: Adapting to overdispersion By projecteuclid.org Published On :: Wed, 15 Apr 2020 22:05 EDT Kerstin Spitzer, Marta Pelizzola, Andreas Futschik. Source: The Annals of Applied Statistics, Volume 14, Number 1, 202--220.Abstract: Evolve and resequence studies provide a popular approach to simulate evolution in the lab and explore its genetic basis. In this context, Pearson’s chi-square test, Fisher’s exact test as well as the Cochran–Mantel–Haenszel test are commonly used to infer genomic positions affected by selection from temporal changes in allele frequency. However, the null model associated with these tests does not match the null hypothesis of actual interest. Indeed, due to genetic drift and possibly other additional noise components such as pool sequencing, the null variance in the data can be substantially larger than accounted for by these common test statistics. This leads to $p$-values that are systematically too small and, therefore, a huge number of false positive results. Even, if the ranking rather than the actual $p$-values is of interest, a naive application of the mentioned tests will give misleading results, as the amount of overdispersion varies from locus to locus. We therefore propose adjusted statistics that take the overdispersion into account while keeping the formulas simple. This is particularly useful in genome-wide applications, where millions of SNPs can be handled with little computational effort. We then apply the adapted test statistics to real data from Drosophila and investigate how information from intermediate generations can be included when available. We also discuss further applications such as genome-wide association studies based on pool sequencing data and tests for local adaptation. Full Article
qua Assessing wage status transition and stagnation using quantile transition regression By projecteuclid.org Published On :: Wed, 15 Apr 2020 22:05 EDT Chih-Yuan Hsu, Yi-Hau Chen, Ruoh-Rong Yu, Tsung-Wei Hung. Source: The Annals of Applied Statistics, Volume 14, Number 1, 160--177.Abstract: Workers in Taiwan overall have been suffering from long-lasting wage stagnation since the mid-1990s. In particular, there seems to be little mobility for the wages of Taiwanese workers to transit across wage quantile groups. It is of interest to see if certain groups of workers, such as female, lower educated and younger generation workers, suffer from the problem more seriously than the others. This work tries to apply a systematic statistical approach to study this issue, based on the longitudinal data from the Panel Study of Family Dynamics (PSFD) survey conducted in Taiwan since 1999. We propose the quantile transition regression model, generalizing recent methodology for quantile association, to assess the wage status transition with respect to the marginal wage quantiles over time as well as the effects of certain demographic and job factors on the wage status transition. Estimation of the model can be based on the composite likelihoods utilizing the binary, or ordinal-data information regarding the quantile transition, with the associated asymptotic theory established. A goodness-of-fit procedure for the proposed model is developed. The performances of the estimation and the goodness-of-fit procedures for the quantile transition model are illustrated through simulations. The application of the proposed methodology to the PSFD survey data suggests that female, private-sector workers with higher age and education below postgraduate level suffer from more severe wage status stagnation than the others. Full Article
qua Prediction of small area quantiles for the conservation effects assessment project using a mixed effects quantile regression model By projecteuclid.org Published On :: Wed, 27 Nov 2019 22:01 EST Emily Berg, Danhyang Lee. Source: The Annals of Applied Statistics, Volume 13, Number 4, 2158--2188.Abstract: Quantiles of the distributions of several measures of erosion are important parameters in the Conservation Effects Assessment Project, a survey intended to quantify soil and nutrient loss on crop fields. Because sample sizes for domains of interest are too small to support reliable direct estimators, model based methods are needed. Quantile regression is appealing for CEAP because finding a single family of parametric models that adequately describes the distributions of all variables is difficult and small area quantiles are parameters of interest. We construct empirical Bayes predictors and bootstrap mean squared error estimators based on the linearly interpolated generalized Pareto distribution (LIGPD). We apply the procedures to predict county-level quantiles for four types of erosion in Wisconsin and validate the procedures through simulation. Full Article
qua Weighted Lépingle inequality By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Pavel Zorin-Kranich. Source: Bernoulli, Volume 26, Number 3, 2311--2318.Abstract: We prove an estimate for weighted $p$th moments of the pathwise $r$-variation of a martingale in terms of the $A_{p}$ characteristic of the weight. The novelty of the proof is that we avoid real interpolation techniques. Full Article
qua Noncommutative Lebesgue decomposition and contiguity with applications in quantum statistics By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Akio Fujiwara, Koichi Yamagata. Source: Bernoulli, Volume 26, Number 3, 2105--2142.Abstract: We herein develop a theory of contiguity in the quantum domain based upon a novel quantum analogue of the Lebesgue decomposition. The theory thus formulated is pertinent to the weak quantum local asymptotic normality introduced in the previous paper [Yamagata, Fujiwara, and Gill, Ann. Statist. 41 (2013) 2197–2217], yielding substantial enlargement of the scope of quantum statistics. Full Article
qua First-order covariance inequalities via Stein’s method By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Marie Ernst, Gesine Reinert, Yvik Swan. Source: Bernoulli, Volume 26, Number 3, 2051--2081.Abstract: We propose probabilistic representations for inverse Stein operators (i.e., solutions to Stein equations) under general conditions; in particular, we deduce new simple expressions for the Stein kernel. These representations allow to deduce uniform and nonuniform Stein factors (i.e., bounds on solutions to Stein equations) and lead to new covariance identities expressing the covariance between arbitrary functionals of an arbitrary univariate target in terms of a weighted covariance of the derivatives of the functionals. Our weights are explicit, easily computable in most cases and expressed in terms of objects familiar within the context of Stein’s method. Applications of the Cauchy–Schwarz inequality to these weighted covariance identities lead to sharp upper and lower covariance bounds and, in particular, weighted Poincaré inequalities. Many examples are given and, in particular, classical variance bounds due to Klaassen, Brascamp and Lieb or Otto and Menz are corollaries. Connections with more recent literature are also detailed. Full Article
qua On the best constant in the martingale version of Fefferman’s inequality By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Adam Osękowski. Source: Bernoulli, Volume 26, Number 3, 1912--1926.Abstract: Let $X=(X_{t})_{tgeq 0}in H^{1}$ and $Y=(Y_{t})_{tgeq 0}in{mathrm{BMO}} $ be arbitrary continuous-path martingales. The paper contains the proof of the inequality egin{equation*}mathbb{E}int _{0}^{infty }iglvert dlangle X,Y angle_{t}igrvert leq sqrt{2}Vert XVert _{H^{1}}Vert YVert _{mathrm{BMO}_{2}},end{equation*} and the constant $sqrt{2}$ is shown to be the best possible. The proof rests on the construction of a certain special function, enjoying appropriate size and concavity conditions. Full Article
qua Logarithmic Sobolev inequalities for finite spin systems and applications By projecteuclid.org Published On :: Mon, 27 Apr 2020 04:02 EDT Holger Sambale, Arthur Sinulis. Source: Bernoulli, Volume 26, Number 3, 1863--1890.Abstract: We derive sufficient conditions for a probability measure on a finite product space (a spin system ) to satisfy a (modified) logarithmic Sobolev inequality. We establish these conditions for various examples, such as the (vertex-weighted) exponential random graph model, the random coloring and the hard-core model with fugacity. This leads to two separate branches of applications. The first branch is given by mixing time estimates of the Glauber dynamics. The proofs do not rely on coupling arguments, but instead use functional inequalities. As a byproduct, this also yields exponential decay of the relative entropy along the Glauber semigroup. Secondly, we investigate the concentration of measure phenomenon (particularly of higher order) for these spin systems. We show the effect of better concentration properties by centering not around the mean, but around a stochastic term in the exponential random graph model. From there, one can deduce a central limit theorem for the number of triangles from the CLT of the edge count. In the Erdős–Rényi model the first-order approximation leads to a quantification and a proof of a central limit theorem for subgraph counts. Full Article
qua Around the entropic Talagrand inequality By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Giovanni Conforti, Luigia Ripani. Source: Bernoulli, Volume 26, Number 2, 1431--1452.Abstract: In this article, we study generalization of the classical Talagrand transport-entropy inequality in which the Wasserstein distance is replaced by the entropic transportation cost. This class of inequalities has been introduced in the recent work ( Probab. Theory Related Fields 174 (2019) 1–47), in connection with the study of Schrödinger bridges. We provide several equivalent characterizations in terms of reverse hypercontractivity for the heat semigroup, contractivity of the Hamilton–Jacobi–Bellman semigroup and dimension-free concentration of measure. Properties such as tensorization and relations to other functional inequalities are also investigated. In particular, we show that the inequalities studied in this article are implied by a Logarithmic Sobolev inequality and imply Talagrand inequality. Full Article
qua Stratonovich stochastic differential equation with irregular coefficients: Girsanov’s example revisited By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Ilya Pavlyukevich, Georgiy Shevchenko. Source: Bernoulli, Volume 26, Number 2, 1381--1409.Abstract: In this paper, we study the Stratonovich stochastic differential equation $mathrm{d}X=|X|^{alpha }circ mathrm{d}B$, $alpha in (-1,1)$, which has been introduced by Cherstvy et al. ( New J. Phys. 15 (2013) 083039) in the context of analysis of anomalous diffusions in heterogeneous media. We determine its weak and strong solutions, which are homogeneous strong Markov processes spending zero time at $0$: for $alpha in (0,1)$, these solutions have the form egin{equation*}X_{t}^{ heta }=((1-alpha)B_{t}^{ heta })^{1/(1-alpha )},end{equation*} where $B^{ heta }$ is the $ heta $-skew Brownian motion driven by $B$ and starting at $frac{1}{1-alpha }(X_{0})^{1-alpha }$, $ heta in [-1,1]$, and $(x)^{gamma }=|x|^{gamma }operatorname{sign}x$; for $alpha in (-1,0]$, only the case $ heta =0$ is possible. The central part of the paper consists in the proof of the existence of a quadratic covariation $[f(B^{ heta }),B]$ for a locally square integrable function $f$ and is based on the time-reversion technique for Markovian diffusions. Full Article
qua On stability of traveling wave solutions for integro-differential equations related to branching Markov processes By projecteuclid.org Published On :: Fri, 31 Jan 2020 04:06 EST Pasha Tkachov. Source: Bernoulli, Volume 26, Number 2, 1354--1380.Abstract: The aim of this paper is to prove stability of traveling waves for integro-differential equations connected with branching Markov processes. In other words, the limiting law of the left-most particle of a (time-continuous) branching Markov process with a Lévy non-branching part is demonstrated. The key idea is to approximate the branching Markov process by a branching random walk and apply the result of Aïdékon [ Ann. Probab. 41 (2013) 1362–1426] on the limiting law of the latter one. Full Article