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几何与自适应 k 均值聚类的渐近理论AI 解读

We revisit Pollard’s classical result on consistency for k-means clustering in Euclidean space, with a focus on extensions in two directions: first, to problems where the data may come from interesting geometric settings (e.g., Riemannian manifolds, reflexive Banach spaces or the Wasserstein space); second, to problems where some parameters are chosen adaptively from the data (e.g., k-medoids or elbow-method k-means). Toward this end, we provide a general theory, which shows…

论多路主成分分析AI 解读

Multiway data are becoming more and more common. While there are many approaches to extending principal component analysis (PCA) from usual data matrices to these types of data, the conceptual differences from the usual PCA, and their methodological implications remain largely unknown. This work aims to specifically address these questions. Through a careful and rigorous treatment, we provide a better understanding of the operating characteristics of multiway PCA, develop…

“无需”统一重叠的策略学习：悲观原则与广义经验 Bernstein 不等式AI 解读

This paper studies offline policy learning, which aims at utilizing observations collected a priori (from either fixed or adaptively evolving behavior policies) to learn an optimal individualized decision rule that achieves the best overall outcomes for a given population. Existing policy learning methods rely on a uniform overlap assumption, that is, the propensities of exploring all actions for all individual characteristics must be lower bounded; the performance of the…

算法稳定性保证分布无关预测方法的训练条件覆盖AI 解读

In a supervised learning problem, given a predicted value that is the output of some trained model, how can we quantify our uncertainty around this prediction? Distribution-free predictive inference aims to construct prediction intervals around this output, with valid coverage that does not rely on assumptions on the distribution of the data or the nature of the model training algorithm. Existing methods in this area, including conformal prediction and jackknife+, offer…

利用异质数据学习个体最优策略的强化学习AI 解读

Offline reinforcement learning (RL) aims to find optimal policies in dynamic environments in order to maximize the expected total rewards by leveraging pre-collected data. Learning from heterogeneous data is one of the fundamental challenges in offline RL. Traditional methods focus on learning an optimal policy for all individuals with pre-collected data from a single episode or homogeneous batch episodes, and thus, may result in a suboptimal policy for a heterogeneous…

可逆混合 Gibbs 链的谱隙界AI 解读

Hybrid Gibbs samplers represent a prominent class of approximated Gibbs algorithms that utilize Markov chains to approximate conditional distributions, with the Metropolis-within-Gibbs algorithm standing out as a well-known example. Despite their widespread use in both statistical and non-statistical applications, little is known about their convergence properties. This article introduces novel methods for establishing bounds on the convergence rates of certain reversible…

固定与随机协变量下的协方差回归分析AI 解读

Covariance regression analysis is an approach to linking the covariance of responses to a set of explanatory variables X, where X can be a vector, matrix, or tensor. Most of the literature on this topic focuses on the “Fixed-X” setting and treats X as nonrandom. By contrast, treating explanatory variables X as random, namely the “Random-X” setting, is often more realistic in practice. This article aims to fill this gap in the literature on the estimation and model assessment…

中高维协变量下完全随机实验的去偏回归调整AI 解读

Completely randomized experiment is the gold standard for causal inference. When the covariate information for each experimental candidate is available, one typical way is to include them in covariate adjustments for more accurate treatment effect estimation. In this paper, we investigate this problem under the randomization-based framework, i.e., that the covariates and potential outcomes of all experimental candidates are assumed as deterministic quantities and the…

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纵向网络数据的半参数建模与分析AI 解读

We introduce a semiparametric latent space model for analyzing longitudinal network data. The model consists of a static latent space component and a time-varying node-specific baseline component. We develop a semiparametric efficient score equation for the latent space parameter by adjusting for the baseline nuisance component. Estimation is accomplished through a one-step update estimator and an appropriately penalized maximum likelihood estimator. We derive oracle error…

熵型协方差模型AI 解读

In covariance matrix estimation, one of the challenges lies in finding a suitable model and an efficient estimation method. Two commonly used modelling approaches in the literature involve imposing linear restrictions on the covariance matrix or its inverse. Another approach considers linear restrictions on the matrix logarithm of the covariance matrix. In this paper, we present a general framework for linear restrictions on different transformations of the covariance…

存在期限结构时的稳健双重差分分析AI 解读

For variables with a term structure, the standard difference-in-differences (DiD) model is predisposed toward misspecification, even under random assignment, because of heterogeneity over the maturity spectrum and imperfect matching between treated and control units. Estimated treatment effects that are false, biased, or hard to interpret become a concern. Neither unit fixed effects nor standard term-structure controls resolve the problem. Solutions that overcome imperfect…

污染资产再配置：环境……的影响（原题截断）AI 解读

This paper investigates how firms’ pollution incentives are influenced by their ability to divest polluted assets. My empirical setting is a major reform that exempts purchasers from liability for past contamination. Using a difference-in-differences framework, I find that the reform reduces toxic emissions, lowers bankruptcy risk, and increases firm value. Cross-sectional tests show that the decline in emissions is driven by firms with weaker financial health and fewer…

具有局部单位根的数据中的伪因子AI 解读

This paper extends the spurious factor analysis of Onatski and Wang (2021, Spurious factor analysis. Econometrica , 89(2), 591–614.) to high-dimensional data with heterogeneous local-to-unit roots. We find a spurious factor phenomenon similar to that observed in the data with unit roots. Namely, the “factors” estimated by the principal components analysis converge to principal eigenfunctions of a weighted average of the covariance kernels of the demeaned Ornstein–Uhlenbeck…

识别与统计决策理论AI 解读

Econometricians have usefully separated study of estimation into identification and statistical components. Identification analysis, which assumes knowledge of the probability distribution generating observable data, places an upper bound on what may be learned about population parameters of interest with finite-sample data. Yet Wald’s statistical decision theory studies decision-making with sample data without reference to identification, indeed without reference to…

跳跃扩散模型的渐近理论AI 解读

This paper presents an asymptotic theory for recurrent jump diffusion models with well-defined scale functions. The class of such models is broad, including general nonstationary as well as stationary jump diffusions with state-dependent jump sizes and intensities. The asymptotics for recurrent jump diffusion models with scale functions are largely comparable to the asymptotics for the corresponding diffusion models without jumps. For stationary jump diffusions, our…

平稳持久数据下的时变参数回归AI 解读

We consider local level and local linear estimators for estimation and inference in time-varying parameter (TVP) regressions with general stationary covariates. The latter estimator also yields estimates for parameter derivatives that are utilized for the development of time invariance tests for the regression coefficients. Our theoretical framework is general enough to allow for a wide range of stationary regressors, including stationary long memory. We demonstrate that…

线性随机系数模型中的有界支持：识别与变量选择AI 解读

We consider linear random coefficient regression models, where the regressors are allowed to have a finite support. First, we investigate identification, and show that the means and the variances and covariances of the random coefficients are identified from the first two conditional moments of the response given the covariates if the support of the covariates, excluding the intercept, contains a Cartesian product with at least three points in each coordinate. We also…

动态二元选择面板数据模型的半参数估计AI 解读

We propose a new approach to the semiparametric analysis of panel data binary choice models with fixed effects and dynamics (lagged dependent variables). The model under consideration has the same random utility framework as in Honoré and Kyriazidou (2000, Econometrica 68, 839–874). We demonstrate that, with additional serial dependence conditions on the process of deterministic utility and tail restrictions on the error distribution, the (point) identification of the model…

结合代理变量与叙事符号限制：重新考察技术冲击的影响AI 解读

ABSTRACT This paper proposes a novel integration of the proxy structural vector autoregression approach with narrative sign restrictions to identify multiple shocks with multiple instrumental variables. We show that this combination leads to informative inferences on shock effects through both analytical demonstrations and Monte Carlo simulations. Applying this method to identify anticipated and unanticipated technology shocks, we find that anticipated shocks account for…

重新考察高维选择中的群体差异：方法及国会演讲应用AI 解读

ABSTRACT Gentzkow, Shapiro, and Taddy, Econometrica 87, no. 4, 2019 (henceforth GST), use a supervised text‐based regression model to assess changes in partisanship in US congressional speech over time. Their estimates imply that partisanship is far greater in recent years than in the past and that it increased sharply in the early 1990s. The paper at hand provides a replication in the wide sense of GST by complementing their analysis in three ways. First, we propose an…

内生转换模型中的异质性与异方差：医生建议对热量摄入的影响AI 解读

ABSTRACT We describe two‐step control function estimation procedures for estimating average treatment effects in constant coefficient endogenous switching models with a binary treatment. We allow for additional heterogeneity by allowing for heteroskedasticity in the latent error in the treatment assignment equation. We apply our estimation procedures to evaluate the causal effect of physician advice on calorie consumption using National Health and Nutritional Examination…

工作场所同伴对未来工资的影响AI 解读

ABSTRACT This paper examines workplace peer effects in two directions, leveraging employer‐employee data for Italy. First, using a novel estimation approach and addressing endogenous worker‐peer sorting, we estimate that a 10% increase in peer quality raises one's wage by 1.8% in the next year. The effect declines to 0.7% after 5 years. Second, in an event study around mobility episodes, we quantify wage changes associated with the entry and leave of high‐quality and…

趋势工资通胀的度量AI 解读

ABSTRACT We extend time‐series models that have so far been used to study price inflation and apply them to a microlevel data set containing worker‐level information on hourly wages. We construct a measure of aggregate nominal wage growth that (i) filters out noise and very transitory movements, (ii) quantifies the importance of idiosyncratic factors for aggregate wage dynamics, and (iii) strongly co‐moves with labor market tightness, unlike existing indicators of wage…

利用动态因子模型为 DSGE 模型提供信息AI 解读

ABSTRACT Structural dynamic factor models (SDFM) represent a reliable tool to inform the construction of dynamic stochastic general equilibrium (DSGE) models. The reason is that the log‐linear solution of a DSGE model has a factor structure which ensures consistency between the representations of the two models. We assess the usefulness of SDFM for DSGE analysis by means of simulations. Using a standard DSGE model as the data generating process, we show that the factor model…