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作者：Wong, Raymond K. W.; Chan, Kwun Chuen Gary
作者单位：Texas A&M University System; Texas A&M University College Station; University of Washington; University of Washington Seattle
摘要：Covariate balance is often advocated for objective causal inference since it mimics randomization in observational data. Unlike methods that balance specific moments of covariates, our proposal attains uniform approximate balance for covariate functions in a reproducing-kernel Hilbert space. The corresponding infinite-dimensional optimization problem is shown to have a finite-dimensional representation in terms of an eigenvalue optimization problem. Large-sample results are studied, and numeri...
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作者：Wang, Lan; Van Keilegom, Ingrid; Maidman, Adam
作者单位：University of Minnesota System; University of Minnesota Twin Cities; KU Leuven
摘要：We consider a heteroscedastic regression model in which some of the regression coefficients are zero but it is not known which ones. Penalized quantile regression is a useful approach for analysing such data. By allowing different covariates to be relevant for modelling conditional quantile functions at different quantile levels, it provides a more complete picture of the conditional distribution of a response variable than mean regression. Existing work on penalized quantile regression has be...
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作者：Molstad, Aaron J.; Rothman, Adam J.
作者单位：Fred Hutchinson Cancer Center; University of Minnesota System; University of Minnesota Twin Cities
摘要：We propose a framework to shrink a user-specified characteristic of a precision matrix estimator that is needed to fit a predictive model. Estimators in our framework minimize the Gaussian negative loglikelihood plus an L-1 penalty on a linear or affine function evaluated at the optimization variable corresponding to the precision matrix. We establish convergence rate bounds for these estimators and propose an alternating direction method of multipliers algorithm for their computation. Our sim...
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作者：Yang, S.; Ding, P.
作者单位：North Carolina State University; University of California System; University of California Berkeley
摘要：Causal inference with observational studies often relies on the assumptions of unconfoundedness and overlap of covariate distributions in different treatment groups. The overlap assumption is violated when some units have propensity scores close to 0 or 1, so both practical and theoretical researchers suggest dropping units with extreme estimated propensity scores. However, existing trimming methods often do not incorporate the uncertainty in this design stage and restrict inference to only th...
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作者：Spady, R. H.; Stouli, S.
作者单位：University of Oxford; University of Bristol
摘要：We propose dual regression as an alternative to quantile regression for the global estimation of conditional distribution functions. Dual regression provides the interpretational power of quantile regression while avoiding the need to repair intersecting conditional quantile surfaces. We introduce a mathematical programming characterization of conditional distribution functions which, in its simplest form, is the dual program of a simultaneous estimator for linear location-scale models, and us...
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作者：Charkhi, Ali; Claeskens, Gerda
作者单位：KU Leuven
摘要：Ignoring the model selection step in inference after selection is harmful. In this paper we study the asymptotic distribution of estimators after model selection using the Akaike information criterion. First, we consider the classical setting in which a true model exists and is included in the candidate set of models. We exploit the overselection property of this criterion in constructing a selection region, and we obtain the asymptotic distribution of estimators and linear combinations thereo...
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作者：Lynch, Brian; Chen, Kehui
作者单位：Pennsylvania Commonwealth System of Higher Education (PCSHE); University of Pittsburgh
摘要：This paper concerns the modelling of multi-way functional data where double or multiple indices are involved. We introduce a concept of weak separability. The weakly separable structure supports the use of factorization methods that decompose the signal into its spatial and temporal components. The analysis reveals interesting connections to the usual strongly separable covariance structure, and provides insights into tensor methods for multi-way functional data. We propose a formal test for t...
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作者：McCullagh, Peter; Polson, Nicholas G.
作者单位：University of Chicago
摘要：The main contribution of this paper is a mathematical definition of statistical sparsity, which is expressed as a limiting property of a sequence of probability distributions. The limit is characterized by an exceedance measure H and a rate parameter. > 0, both of which are unrelated to sample size. The definition encompasses all sparsity models that have been suggested in the signal-detection literature. Sparsity implies that. is small, and a sparse approximation is asymptotic in the rate par...
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作者：Avella-Medina, Marco; Ronchetti, Elvezio
作者单位：Massachusetts Institute of Technology (MIT); University of Geneva
摘要：Generalized linear models are popular for modelling a large variety of data. We consider variable selection through penalized methods by focusing on resistance issues in the presence of outlying data and other deviations from assumptions. We highlight the weaknesses of widely-used penalized M-estimators, propose a robust penalized quasilikelihood estimator, and show that it enjoys oracle properties in high dimensions and is stable in a neighbourhood of the model. We illustrate its finite-sampl...
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作者：Lunardon, N.
作者单位：University of Milano-Bicocca
摘要：Firth (1993) introduced a method for reducing the bias of the maximum likelihood estimator. Here it is shown that the approach is also effective in reducing the sensitivity of inferential procedures to incidental parameters.
