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作者：Wang, Shanshan; Jank, Wolfgang; Shmueli, Galit; Smith, Paul
作者单位：University System of Maryland; University of Maryland College Park
摘要：Empirical research of online auctions has grown dramatically in recent years. Studies using publicly available bid data from such wedsites as eBay.com have found many divergences of bidding behavior and auction outcomes compared with ordinary offline auctions and auction theory. Among the main differences between online and offline auctions are the former's longer duration, anonymity of bidders and sellers, and low barriers of entry. All of these factors lead to dynamics in the bid arrival and...
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作者：Hunter, David R.; Goodreau, Steven M.; Handcock, Mark S.
作者单位：Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Washington; University of Washington Seattle; University of Washington; University of Washington Seattle
摘要：We present a systematic examination of a real network data set using maximum likelihood estimation for exponential random graph models as well as new procedures to evaluate how well the models fit the observed networks. These procedures compare structural statistics of the observed network with the corresponding statistics on networks simulated from the fitted model. We apply this approach to the study of friendship relations among high school students from the National Longitudinal Study of A...
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作者：Edwards, A. W. F.
作者单位：University of Cambridge
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作者：Rice, Kenneth
作者单位：University of Washington; University of Washington Seattle
摘要：Two approaches dominate the analysis of highly stratified data sets: use of conditional likelihood and random-effects models. Conditioning is more traditional and has attractive robustness properties. Contemporary random-effects approaches rely more on accurate assumptions but can be applied to a larger class of problems. For pair-matched studies with arbitrary numbers of categorical covariates, we reconcile these two approaches, showing that the conditional approach has an exact interpretatio...
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作者：Fan, Jianqing; Wu, Yichao
作者单位：Princeton University; Shanghai University of Finance & Economics; North Carolina State University
摘要：Estimation of longitudinal data covariance structure Poses significant challenges because the data usually are collected at irregular time points. A viable semiparametric model for covariance matrixes has been proposed that allows one to estimate the variance function nonparametrically and to estimate the correlation function parametrically by aggregating information front irregular and sparse data points within each subject. But the asymptotic properties of the quasi-maximum likelihood estima...
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作者：Lin, Haiqun; Feng, Ziding; Yu, Yan; Zheng, Yingye; Shivapurkar, Narayan; Gazdar, Adi F.
作者单位：Yale University; Fred Hutchinson Cancer Center; University System of Ohio; University of Cincinnati; University of Texas System; University of Texas Southwestern Medical Center
摘要：Alteration of gene methylation patterns has been reported to be involved in the early onsets of many human malignancies. Many exogenous risk factors, such as cigarette smoke, dietary additives, chemical exposures, radiation, and biologic agents including viral infection, are involved in the methylation pathways of cancers. We propose a multidimensional selective item response regression model to describe and test how a risk factor may alter molecular pathways involving aberrant methylation of ...
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作者：Kaufman, Cari G.; Schervish, Mark J.; Nychka, Douglas W.
作者单位：University of California System; University of California Berkeley; Carnegie Mellon University; National Center Atmospheric Research (NCAR) - USA
摘要：Maximum likelihood is an attractive method of estimating covariance parameters in spatial models based oil Gaussian processes. But calculating, the likelihood can he computationally infeasible for large data sets, requiring O(m(3)) calculations for a data set with a observations. This article proposes the method of covariance tapering to approximate the likelihood in this setting. In this approach. covariance matrixes are tapered. or multiplied element wise by a sparse correlation matrix. The ...
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作者：Kneip, Alois; Ramsay, James O.
作者单位：University of Bonn; University of Bonn
摘要：A registration method can be defined as a process of aligning features of a sample of curves by monotone transformations of their domain. The aligned curves exhibit only amplitude variation, and the domain transformations, called warping functions, capture the phase variation in the original curves. In this article we precisely define a new type of registration process, in which the warping functions optimize the fit of a principal components decomposition to the aligned curves. The principal ...
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作者：Ellis, Byron; Wong, Wing Hung
作者单位：Stanford University
摘要：We propose a method for the computational inference of directed acyclic graphical structures given data from experimental interventions. Order-space Markov chain Monte Carlo, equi-energy sampling, importance weighting, and stream-based computation are combined to create a fast algorithm for learning causal Bayesian network structures.
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作者：Dror, Hovav A.; Steinberg, David M.
作者单位：Tel Aviv University
摘要：We consider the problem of experimental design when the response is modeled by a generalized linear model (GLM) and the experimental plan can be determined sequentially. Most previous research on this problem has been limited either to one-factor, binary response experiments or to augmenting the design when there are already sufficient data to compute parameter estimates. We suggest a new procedure for the sequential choice of observations that offers five important advantages: (1) It can be a...
