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作者：Morris, JS; Vannucci, M; Brown, PJ; Carroll, RJ
作者单位：University of Texas System; UTMD Anderson Cancer Center; Texas A&M University System; Texas A&M University College Station; University of Kent; Texas A&M University System; Texas A&M University College Station
摘要：In this article we develop new methods for analyzing the data from an experiment using rodent models to investigate the effect of type of dietary fat on O-6-methylguanine-DNA-methyltransferase (MGMT), an important biomarker in early colon carcinogenesis. The data consist of observed profiles over a spatial variable contained within a two-stage hierarchy, a structure that we dub hierarchical functional data. We present a new method providing a unified framework for modeling these data, simultan...
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作者：Chen, WW; Hurvich, CM
作者单位：Texas A&M University System; Texas A&M University College Station; New York University
摘要：We consider the semiparametric estimation of fractional cointegration in a multivariate process of cointegrating rank r > 0. We estimate the cointegrating relationships by the eigenvectors corresponding to the r smallest eigenvalues of an averaged periodogram matrix of tapered, differenced observations. The number of frequencies m used in the periodogram average is held fixed as the sample size grows. We first show that the averaged periodogram matrix converges in distribution to a singular ma...
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作者：Dubinin, TM; Vardeman, SB
作者单位：Iowa State University; Iowa State University
摘要：We study likelihood-based inference in some continuous exponential families with unknown threshold parameters. The introduction of threshold parameters necessitates modification of the standard asymptotic arguments, and some possibly unexpected limiting distributions result.
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作者：Sugar, CA; James, GM
作者单位：University of Southern California
摘要：One of the most difficult problems in cluster analysis is identifying the number of groups in a dataset. Most previously suggested approaches to this problem are either somewhat ad hoc or require parametric assumptions and complicated calculations. In. this article we develop a simple, yet powerful nonparametric method for choosing the number of clusters based on distortion, a quantity that measures the average distance, per dimension, between each observation and its closest cluster center. O...
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作者：Huang, Y; Wang, CY
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作者：Jupp, PE; Kim, PT; Koo, JY; Wiegert, P
作者单位：University of St Andrews; University of Guelph; Inha University; Queens University - Canada
摘要：A question that arises in the study of cometary orbits is whether or not the directed normals to the orbits are uniformly distributed on the celestial sphere. Previous studies by statisticians have not taken selection effects into account and have tended to reject uniformity. Here a plausible selection mechanism is proposed that gives rise to a one-parameter family of distributions on the sphere. Data on long-period comets are analyzed using this one-parameter family. A nonzero selection effec...
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作者：Boatwright, P; Borle, S; Kadane, JB
作者单位：Carnegie Mellon University; Rice University
摘要：Prediction of purchase timing and quantity decisions of a household is an important element for success of any retailer. This is especially so for an online retailer, as the traditional brick and-mortar retailer would be more concerned with total sales. A number of statistical models have been developed in the marketing literature to aid traditional retailers in predicting sales and analyzing the impact of various marketing activities on sales. However, there are two important differences betw...
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作者：Hu, FF; Rosenberger, WF
作者单位：University of Virginia; National University of Singapore; University System of Maryland; University of Maryland Baltimore County; University System of Maryland; University of Maryland Baltimore; National University of Singapore
摘要：We provide a theoretical template for the comparison of response-adaptive randomization procedures for clinical trials. Using a Taylor expansion of the noncentrality parameter of the usual chi-squared test for binary responses, we show explicitly the relationship among the target allocation proportion, the bias of the randomization procedure from that target, and the variability induced by the randomization procedure. We also generalize this relationship for more than two treatments under vari...
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作者：Puig, P
作者单位：Autonomous University of Barcelona
摘要：This article reports on two-parameter count distributions (satisfying very general conditions) that are closed under addition so that their maximum likelihood estimator (MLE) of the population mean is the sample mean. The most important of these in practice, the generalized Hermite distribution, is analyzed, and a necessary and sufficient condition is given to ensure that the MLE is the solution of likelihood equations. Score test to contrast the Poisson assumption is studied, and two examples...
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作者：Dunson, DB
作者单位：National Institutes of Health (NIH) - USA; NIH National Institute of Environmental Health Sciences (NIEHS)
摘要：This article presents a new approach for analysis of multidimensional longitudinal data, motivated by studies using an item response battery to measure traits of an individual repeatedly over time. A general modeling framework is proposed that allows mixtures of count, categorical, and continuous response variables. Each response is related to age-specific latent traits through a generalized linear model that accommodates item-specific measurement errors. A transition model allows the latent t...
