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Models as Approximations II: A Model-Free Theory of Parametric Regression

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.




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Models as Approximations I: Consequences Illustrated with Linear Regression

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.




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Assessing the Causal Effect of Binary Interventions from Observational Panel Data with Few Treated Units

Pantelis Samartsidis, Shaun R. Seaman, Anne M. Presanis, Matthew Hickman, Daniela De Angelis.

Source: Statistical Science, Volume 34, Number 3, 486--503.

Abstract:
Researchers are often challenged with assessing the impact of an intervention on an outcome of interest in situations where the intervention is nonrandomised, the intervention is only applied to one or few units, the intervention is binary, and outcome measurements are available at multiple time points. In this paper, we review existing methods for causal inference in these situations. We detail the assumptions underlying each method, emphasize connections between the different approaches and provide guidelines regarding their practical implementation. Several open problems are identified thus highlighting the need for future research.




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Conditionally Conjugate Mean-Field Variational Bayes for Logistic Models

Daniele Durante, Tommaso Rigon.

Source: Statistical Science, Volume 34, Number 3, 472--485.

Abstract:
Variational Bayes (VB) is a common strategy for approximate Bayesian inference, but simple methods are only available for specific classes of models including, in particular, representations having conditionally conjugate constructions within an exponential family. Models with logit components are an apparently notable exception to this class, due to the absence of conjugacy among the logistic likelihood and the Gaussian priors for the coefficients in the linear predictor. To facilitate approximate inference within this widely used class of models, Jaakkola and Jordan ( Stat. Comput. 10 (2000) 25–37) proposed a simple variational approach which relies on a family of tangent quadratic lower bounds of the logistic log-likelihood, thus restoring conjugacy between these approximate bounds and the Gaussian priors. This strategy is still implemented successfully, but few attempts have been made to formally understand the reasons underlying its excellent performance. Following a review on VB for logistic models, we cover this gap by providing a formal connection between the above bound and a recent Pólya-gamma data augmentation for logistic regression. Such a result places the computational methods associated with the aforementioned bounds within the framework of variational inference for conditionally conjugate exponential family models, thereby allowing recent advances for this class to be inherited also by the methods relying on Jaakkola and Jordan ( Stat. Comput. 10 (2000) 25–37).




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The Geometry of Continuous Latent Space Models for Network Data

Anna L. Smith, Dena M. Asta, Catherine A. Calder.

Source: Statistical Science, Volume 34, Number 3, 428--453.

Abstract:
We review the class of continuous latent space (statistical) models for network data, paying particular attention to the role of the geometry of the latent space. In these models, the presence/absence of network dyadic ties are assumed to be conditionally independent given the dyads’ unobserved positions in a latent space. In this way, these models provide a probabilistic framework for embedding network nodes in a continuous space equipped with a geometry that facilitates the description of dependence between random dyadic ties. Specifically, these models naturally capture homophilous tendencies and triadic clustering, among other common properties of observed networks. In addition to reviewing the literature on continuous latent space models from a geometric perspective, we highlight the important role the geometry of the latent space plays on properties of networks arising from these models via intuition and simulation. Finally, we discuss results from spectral graph theory that allow us to explore the role of the geometry of the latent space, independent of network size. We conclude with conjectures about how these results might be used to infer the appropriate latent space geometry from observed networks.




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An Overview of Semiparametric Extensions of Finite Mixture Models

Sijia Xiang, Weixin Yao, Guangren Yang.

Source: Statistical Science, Volume 34, Number 3, 391--404.

Abstract:
Finite mixture models have offered a very important tool for exploring complex data structures in many scientific areas, such as economics, epidemiology and finance. Semiparametric mixture models, which were introduced into traditional finite mixture models in the past decade, have brought forth exciting developments in their methodologies, theories, and applications. In this article, we not only provide a selective overview of the newly-developed semiparametric mixture models, but also discuss their estimation methodologies, theoretical properties if applicable, and some open questions. Recent developments are also discussed.




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A Conversation with Noel Cressie

Christopher K. Wikle, Jay M. Ver Hoef.

Source: Statistical Science, Volume 34, Number 2, 349--359.

Abstract:
Noel Cressie, FAA is Director of the Centre for Environmental Informatics in the National Institute for Applied Statistics Research Australia (NIASRA) and Distinguished Professor in the School of Mathematics and Applied Statistics at the University of Wollongong, Australia. He is also Adjunct Professor at the University of Missouri (USA), Affiliate of Org 398, Science Data Understanding, at NASA’s Jet Propulsion Laboratory (USA), and a member of the Science Team for NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite. Cressie was awarded a B.Sc. with First Class Honours in Mathematics in 1972 from the University of Western Australia, and an M.A. and Ph.D. in Statistics in 1973 and 1975, respectively, from Princeton University (USA). Two brief postdoctoral periods followed, at the Centre de Morphologie Mathématique, ENSMP, in Fontainebleau (France) from April 1975–September 1975, and at Imperial College, London (UK) from September 1975–January 1976. His past appointments have been at The Flinders University of South Australia from 1976–1983, at Iowa State University (USA) from 1983–1998, and at The Ohio State University (USA) from 1998–2012. He has authored or co-authored four books and more than 280 papers in peer-reviewed outlets, covering areas that include spatial and spatio-temporal statistics, environmental statistics, empirical-Bayesian and Bayesian methods including sequential design, goodness-of-fit, and remote sensing of the environment. Many of his papers also address important questions in the sciences. Cressie is a Fellow of the Australian Academy of Science, the American Statistical Association, the Institute of Mathematical Statistics, and the Spatial Econometrics Association, and he is an Elected Member of the International Statistical Institute. Noel Cressie’s refereed, unrefereed, and other publications are available at: https://niasra.uow.edu.au/cei/people/UOW232444.html.




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Producing Official County-Level Agricultural Estimates in the United States: Needs and Challenges

Nathan B. Cruze, Andreea L. Erciulescu, Balgobin Nandram, Wendy J. Barboza, Linda J. Young.

Source: Statistical Science, Volume 34, Number 2, 301--316.

Abstract:
In the United States, county-level estimates of crop yield, production, and acreage published by the United States Department of Agriculture’s National Agricultural Statistics Service (USDA NASS) play an important role in determining the value of payments allotted to farmers and ranchers enrolled in several federal programs. Given the importance of these official county-level crop estimates, NASS continually strives to improve its crops county estimates program in terms of accuracy, reliability and coverage. In 2015, NASS engaged a panel of experts convened under the auspices of the National Academies of Sciences, Engineering, and Medicine Committee on National Statistics (CNSTAT) for guidance on implementing models that may synthesize multiple sources of information into a single estimate, provide defensible measures of uncertainty, and potentially increase the number of publishable county estimates. The final report titled Improving Crop Estimates by Integrating Multiple Data Sources was released in 2017. This paper discusses several needs and requirements for NASS county-level crop estimates that were illuminated during the activities of the CNSTAT panel. A motivating example of planted acreage estimation in Illinois illustrates several challenges that NASS faces as it considers adopting any explicit model for official crops county estimates.




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A Kernel Regression Procedure in the 3D Shape Space with an Application to Online Sales of Children’s Wear

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.




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Comment: Minimalist $g$-Modeling

Roger Koenker, Jiaying Gu.

Source: Statistical Science, Volume 34, Number 2, 209--213.

Abstract:
Efron’s elegant approach to $g$-modeling for empirical Bayes problems is contrasted with an implementation of the Kiefer–Wolfowitz nonparametric maximum likelihood estimator for mixture models for several examples. The latter approach has the advantage that it is free of tuning parameters and consequently provides a relatively simple complementary method.




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Comment: Contributions of Model Features to BART Causal Inference Performance Using ACIC 2016 Competition Data

Nicole Bohme Carnegie.

Source: Statistical Science, Volume 34, Number 1, 90--93.

Abstract:
With a thorough exposition of the methods and results of the 2016 Atlantic Causal Inference Competition, Dorie et al. have set a new standard for reproducibility and comparability of evaluations of causal inference methods. In particular, the open-source R package aciccomp2016, which permits reproduction of all datasets used in the competition, will be an invaluable resource for evaluation of future methodological developments. Building upon results from Dorie et al., we examine whether a set of potential modifications to Bayesian Additive Regression Trees (BART)—multiple chains in model fitting, using the propensity score as a covariate, targeted maximum likelihood estimation (TMLE), and computing symmetric confidence intervals—have a stronger impact on bias, RMSE, and confidence interval coverage in combination than they do alone. We find that bias in the estimate of SATT is minimal, regardless of the BART formulation. For purposes of CI coverage, however, all proposed modifications are beneficial—alone and in combination—but use of TMLE is least beneficial for coverage and results in considerably wider confidence intervals.




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Comment on “Automated Versus Do-It-Yourself Methods for Causal Inference: Lessons Learned from a Data Analysis Competition”

Susan Gruber, Mark J. van der Laan.

Source: Statistical Science, Volume 34, Number 1, 82--85.

Abstract:
Dorie and co-authors (DHSSC) are to be congratulated for initiating the ACIC Data Challenge. Their project engaged the community and accelerated research by providing a level playing field for comparing the performance of a priori specified algorithms. DHSSC identified themes concerning characteristics of the DGP, properties of the estimators, and inference. We discuss these themes in the context of targeted learning.




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Angel over the city.

1990.




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Be nice to yourself and others / design : Biman Mullick.

London : Cleanair, Smoke-free Environment (33 Stillness Rd, London, SE23 1NG), [198-?]




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Elle est classe, elle ne fume pas / Biman Mullick.

London (33 Stillness Road, London SE23 1NG) : Cleanair, [1989?]




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Be nice to yourself and others / design : Biman Mullick.

London : Cleanair, Smoke-free Environment (33 Stillness Rd, London, SE23 1NG), [198-?]




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Elle est classe, elle ne fume pas / Biman Mullick.

London (33 Stillness Rd, SE23 1NG) : Cleanair, [198-?]




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Danny Smith from No Human Being Is Illegal (in all our glory). Collaged photograph by Deborah Kelly and collaborators, 2014-2018.

[London], 2019.




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The 2019 Victoria’s Secret Fashion Show Is Canceled After Facing Backlash for Lack of Body Diversity

The reaction on social media has been fierce.




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Blake Lively's Favorite Affordable Jeans Brand Is Having a Major Sale Right Now

Here's everything you need to know about Old Navy's Black Friday and Cyber Monday plans.




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Taylor Swift, Hailey Bieber, and Tons of Other Celebs’ Favorite Leggings Are on Sale Ahead of Black Friday

Here’s where you can snag their Alo Yoga Moto leggings for less.




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Gabrielle Union's Mesmerizing Tie Dye Activewear Set Is On Sale for Black Friday

The rainbow sports bra and leggings set from Splits59 is a must-have for anyone craving a pop of color in their workout wardrobe.




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Jennifer Lopez Is Wearing the Hell Out of These $60 Sneakers—and You Can Buy Them at Zappos

The chic sneaks are part of Zappos' massive Cyber Monday sale.




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The Comfy Sneakers That Kate Middleton, Kelly Ripa, and More Celebs Love Are on Sale at Amazon

Keep your feet comfy and your wallet fat.




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Allometric Analysis Detects Brain Size-Independent Effects of Sex and Sex Chromosome Complement on Human Cerebellar Organization

Catherine Mankiw
May 24, 2017; 37:5221-5231
Development Plasticity Repair




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Axonal ramifications of hippocampal Ca1 pyramidal cells

WD Knowles
Nov 1, 1981; 1:1236-1241
Articles




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Microglia Actively Remodel Adult Hippocampal Neurogenesis through the Phagocytosis Secretome

Irune Diaz-Aparicio
Feb 12, 2020; 40:1453-1482
Development Plasticity Repair




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{Delta}9-Tetrahydrocannabinol and Cannabinol Activate Capsaicin-Sensitive Sensory Nerves via a CB1 and CB2 Cannabinoid Receptor-Independent Mechanism

Peter M. Zygmunt
Jun 1, 2002; 22:4720-4727
Behavioral




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Afferents and Homotypic Neighbors Regulate Horizontal Cell Morphology, Connectivity, and Retinal Coverage

Benjamin E. Reese
Mar 2, 2005; 25:2167-2175
BehavioralSystemsCognitive




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Astrocytes Modulate Baroreflex Sensitivity at the Level of the Nucleus of the Solitary Tract

Svetlana Mastitskaya
Apr 8, 2020; 40:3052-3062
Systems/Circuits




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Fingolimod Rescues Demyelination in a Mouse Model of Krabbe's Disease

Sibylle Béchet
Apr 8, 2020; 40:3104-3118
Neurobiology of Disease




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Dural Calcitonin Gene-Related Peptide Produces Female-Specific Responses in Rodent Migraine Models

Amanda Avona
May 29, 2019; 39:4323-4331
Systems/Circuits




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A Transcriptome Database for Astrocytes, Neurons, and Oligodendrocytes: A New Resource for Understanding Brain Development and Function

John D. Cahoy
Jan 2, 2008; 28:264-278
Cellular




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Grey Matter Volume Differences Associated with Extremely Low Levels of Cannabis Use in Adolescence

Catherine Orr
Mar 6, 2019; 39:1817-1827
BehavioralSystemsCognitive




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Social Laughter Triggers Endogenous Opioid Release in Humans

Sandra Manninen
Jun 21, 2017; 37:6125-6131
BehavioralSystemsCognitive




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An RNA-Sequencing Transcriptome and Splicing Database of Glia, Neurons, and Vascular Cells of the Cerebral Cortex

Ye Zhang
Sep 3, 2014; 34:11929-11947
Cellular




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Endothelial Adora2a Activation Promotes Blood-Brain Barrier Breakdown and Cognitive Impairment in Mice with Diet-Induced Insulin Resistance

Masaki Yamamoto
May 22, 2019; 39:4179-4192
Neurobiology of Disease




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The Encoding of Sound Source Elevation in the Human Auditory Cortex

Régis Trapeau
Mar 28, 2018; 38:3252-3264
BehavioralSystemsCognitive




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Oscillatory Coupling of Hippocampal Pyramidal Cells and Interneurons in the Behaving Rat

Jozsef Csicsvari
Jan 1, 1999; 19:274-287
Articles




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Gamma Oscillation by Synaptic Inhibition in a Hippocampal Interneuronal Network Model

Xiao-Jing Wang
Oct 15, 1996; 16:6402-6413
Articles




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Head-direction cells recorded from the postsubiculum in freely moving rats. I. Description and quantitative analysis

JS Taube
Feb 1, 1990; 10:420-435
Articles




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Dendritic spines of CA 1 pyramidal cells in the rat hippocampus: serial electron microscopy with reference to their biophysical characteristics

KM Harris
Aug 1, 1989; 9:2982-2997
Articles




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Cellular Composition and Three-Dimensional Organization of the Subventricular Germinal Zone in the Adult Mammalian Brain

Fiona Doetsch
Jul 1, 1997; 17:5046-5061
Articles




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Broadband Shifts in Local Field Potential Power Spectra Are Correlated with Single-Neuron Spiking in Humans

Jeremy R. Manning
Oct 28, 2009; 29:13613-13620
BehavioralSystemsCognitive




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A computational analysis of the relationship between neuronal and behavioral responses to visual motion

MN Shadlen
Feb 15, 1996; 16:1486-1510
Articles




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The effects of changes in the environment on the spatial firing of hippocampal complex-spike cells

RU Muller
Jul 1, 1987; 7:1951-1968
Articles




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Cortical Hubs Revealed by Intrinsic Functional Connectivity: Mapping, Assessment of Stability, and Relation to Alzheimer's Disease

Randy L. Buckner
Feb 11, 2009; 29:1860-1873
Neurobiology of Disease




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A selective impairment of motion perception following lesions of the middle temporal visual area (MT)

WT Newsome
Jun 1, 1988; 8:2201-2211
Articles




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{alpha}-Band Electroencephalographic Activity over Occipital Cortex Indexes Visuospatial Attention Bias and Predicts Visual Target Detection

Gregor Thut
Sep 13, 2006; 26:9494-9502
BehavioralSystemsCognitive




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The highly irregular firing of cortical cells is inconsistent with temporal integration of random EPSPs

WR Softky
Jan 1, 1993; 13:334-350
Articles