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作者：GLAD, IK; SEBASTIANI, G
摘要：Synthetic magnetic resonance imaging involves the estimation, based on a set of measured images with noise, of three basic physical quantities that are nonlinearly related to the observations. The methods currently available for this ill-conditoned inverse problem either do not provide sufficiently accurate estimates or require time-consuming data collection. We formulate this nonlinear problem in a Bayesian framework, taking into account knowledge about the physics of the magnetic resonance i...
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作者：LINTON, O; NIELSEN, JP
摘要：We define a simple kernel procedure based on marginal integration that estimates the relevant univariate quantity in both additive and multiplicative nonparametric regression.
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作者：ELSTER, C; NEUMAIER, A
作者单位：University of Vienna
摘要：Screening experiments aim to identify the relevant variables within some process potentially depending on a large number of variables. In this paper we introduce a new class of experimental designs called edge designs. These designs allow a model-independent estimate of the set of relevant variables, thus providing more robustness than traditional designs. We give a bound on the determinant of the information matrix of certain edge designs, and show that a large class of edge designs meeting t...
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作者：HALL, P; HOROWITZ, JL; JING, BY
作者单位：University of Iowa; Hong Kong University of Science & Technology
摘要：We address the issue of optimal block choice in applications of the block bootstrap to dependent data. It is shown that optimal block size depends significantly on context, being equal to n(1/3), n(1/4) and n(1/5) in the cases of variance or bias estimation, estimation of a one-sided distribution function, and estimation of a two-sided distribution function, respectively. A clear intuitive explanation of this phenomenon is given, together with outlines of theoretical arguments in specific case...
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作者：HJELLVIK, V; TJOSTHEIM, D
摘要：We introduce tests of linearity for time series based on nonparametric estimates of the conditional mean and the conditional variance. The tests are compared to a number of parametric tests and to nonparametric tests based on the bispectrum. Asymptotic expressions give bad approximations, and the null distribution under linearity is constructed using resampling of the best linear approximation. The new tests perform well on the examples tested.
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作者：PIKOUNIS, VB; RAO, PV
作者单位：State University System of Florida; University of Florida
摘要：In a two-sample setting, a two-parameter mixture model is postulated for the treated patients where a proportion of the patients improve and the remaining proportion of nonresponders behave like the control patients. The response is subject to random censoring. Censored data versions of linear rank statistics are developed in order to detect improvement due to treatment. The tests are compared to standard tests such as the log-rank test in terms of asymptotic relative efficiency, empirical pow...
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作者：ZHAO, LP
摘要：Studies in genetic epidemiology are generally required to collect phenotypes on subjects from human pedigrees that consist of blood relatives and their spouses. One of the main objectives in analyzing pedigree data is to study the segregation of underlying genes that may predispose certain phenotypes and thus cause phenotypic aggregation within pedigrees. Most classical segregation methods are maximum likelihood-based under highly specified distributional assumptions for phenotypes given under...
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作者：WELLS, MT
作者单位：Cornell University
摘要：Cox's proportional hazards model assumes that the duration hazard rate factors into a product of a baseline hazard rate and a nonnegative function of explanatory variables. An estimate of the baseline hazard rate, hence also of overall hazard rate, is proposed, based on a smoothing procedure using a kernel function. It is shown that the proposed estimator is uniformly consistent and converges weakly to a Gaussian process. Bandwidth selection issues are also discussed.
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作者：LITTLE, RJA
摘要：Likelihood-based methods are developed for analyzing a random sample on two continuous variables when values of one of the variables are missing. Normal maximum likelihood estimates when values are missing completely at random were derived by Anderson (1957). They are also maximum likelihood providing the missing-data mechanism is ignorable, in Rubin's (1976) sense that the mechanism depends only on observed data. A new class of pattern-mixture models (Little, 1993) is described for the situat...
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作者：MONTI, AC
摘要：This note proposes a test of goodness of fit for time series models based on the sum of the squared residual partial autocorrelations. The test statistic is asymptotically chi(2). Its small-sample performance is studied through a Monte Carlo experiment. It appears sensitive to erroneous specifications especially when the fitted model understates the order of the moving average component.
