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作者：Aldred, R. E. L.; Bailey, R. A.; Mckay, Brendan D.; Wanless, Ian M.
作者单位：University of Otago; University of St Andrews; Australian National University; Monash University
摘要：We define three types of neighbour-balanced designs for experiments where the units are arranged in a circle or single line in space or time. The designs are balanced with respect to neighbours at distance one and at distance two. The variants come from allowing or forbidding self-neighbours, and from considering neighbours to be directed or undirected. For two of the variants, we give a method of constructing a design for all values of the number of treatments, except for some small values wh...
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作者：Wang, T.; Guo, X.; Zhu, L.; Xu, P.
作者单位：Hong Kong Baptist University; Southeast University - China
摘要：We propose a general framework for dimension reduction in regression to fill the gap between linear and fully nonlinear dimension reduction. The main idea is to first transform each of the raw predictors monotonically and then search for a low-dimensional projection in the space defined by the transformed variables. Both user-specified and data-driven transformations are suggested. In each case, the methodology is first discussed in generality and then a representative method is proposed and e...
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作者：Mukerjee, Rahul; Sun, Fasheng; Tang, Boxin
作者单位：Indian Institute of Management (IIM System); Indian Institute of Management Calcutta; Northeast Normal University - China; Simon Fraser University
摘要：We develop a method for construction of arrays which are nearly orthogonal, in the sense that each column is orthogonal to a large proportion of the other columns, and which are convertible to fully orthogonal arrays via a mapping of the symbols in each column to a possibly smaller set of symbols. These arrays can be useful in computer experiments as designs which accommodate a large number of factors and enjoy attractive space-filling properties. Our construction allows both the mappable near...
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作者：Feng, Changyong; Wang, Hongyue; Chen, Tian; Tu, Xin M.
作者单位：University of Rochester
摘要：Exact forms of Taylor expansion for vector-valued functions have been incorrectly used in many statistical publications. We offer two methods to correct this error.
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作者：Vogel, D.; Tyler, D. E.
作者单位：Ruhr University Bochum; Rutgers University System; Rutgers University New Brunswick
摘要：Robust estimators of the restricted covariance matrices associated with elliptical graphical models are studied. General asymptotic results, which apply to both decomposable and nondecomposable graphical models, are presented for robust plug-in type estimators. These extend results previously established only for the decomposable case. Furthermore, a class of graphical M-estimators for the restricted covariance matrices is introduced and compared with the corresponding plug-in M-estimators. Th...
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作者：Lei, Jing
作者单位：Carnegie Mellon University
摘要：A framework for classification is developed with a notion of confidence. In this framework, a classifier consists of two tolerance regions in the predictor space, with a specified coverage level for each class. The classifier also produces an ambiguous region where the classification needs further investigation. Theoretical analysis reveals interesting structures of the confidence-ambiguity trade-off, and the optimal solution is characterized by extending the Neyman-Pearson lemma. We provide g...
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作者：Tchetgen, E. J. Tchetgen; Shpitser, I.
作者单位：Harvard University; Harvard T.H. Chan School of Public Health; University of Southampton
摘要：Establishing cause-effect relationships is a standard goal of empirical science. Once the existence of a causal relationship is established, the precise causal mechanism involved becomes a topic of interest. A particularly popular type of mechanism analysis concerns questions of mediation, i.e., to what extent an effect is direct, and to what extent it is mediated by a third variable. A semiparametric theory has recently been proposed that allows multiply robust estimation of direct and mediat...
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作者：Song, Rui; Lu, Wenbin; Ma, Shuangge; Jeng, X. Jessie
作者单位：North Carolina State University; Yale University
摘要：In modern statistical applications, the dimension of covariates can be much larger than the sample size. In the context of linear models, correlation screening (Fan & Lv, J. R. Statist. Soc. B, 70, 849-911, 2008) has been shown to reduce the dimension of such data effectively while achieving the sure screening property, i.e., all of the active variables can be retained with high probability. However, screening based on the Pearson correlation does not perform well when applied to contaminated ...
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作者：Qin, Jing; Follmann, Dean A.
作者单位：National Institutes of Health (NIH) - USA; NIH National Institute of Allergy & Infectious Diseases (NIAID)
摘要：In marketing research, social science and epidemiological studies, call-back of nonrespondents is standard. If respondents and nonrespondents tend to give different answers, the missing data are called non-ignorable, and using them alone may produce biased results. To extend earlier work on nonresponse in the presence of call-backs, Alho (1990) proposed modelling the probability of response at each attempt through logistic regression, where outcomes of interest and covariates are explanatory v...
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作者：Lin, Wei; Shi, Pixu; Feng, Rui; Li, Hongzhe
作者单位：University of Pennsylvania
摘要：Motivated by research problems arising in the analysis of gut microbiome and metagenomic data, we consider variable selection and estimation in high-dimensional regression with compositional covariates. We propose an l(1) regularization method for the linear log-contrast model that respects the unique features of compositional data. We formulate the proposed procedure as a constrained convex optimization problem and introduce a coordinate descent method of multipliers for efficient computation...
