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作者：LONGFORD, NT
摘要：A fast Fisher scoring algorithm for maximum likelihood estimation in unbalanced mixed models with nested random effects is described. The algorithm uses explicit formulae for the inverse and the determinant of the covariance matrix, given by LaMotte (1972), and avoids inversion of large matrices. Description of the algorithm concentrates on computational aspects for large sets of data.
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作者：PICKANDS, J; RAGHAVACHARI, M
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作者：DUCHARME, GR; MILASEVIC, P
作者单位：University of Fribourg
摘要：We introduce the normalized spatial median as an estimator of location for rotationally symmetric distributions on the hypersphere. We investigate some of its asymptotic properties and use them to obtain confidence regions for the modal direction of a distribution on the hypersphere. These results are then applied to the von Mises-Fisher distribution and to a contamination model. It is seen that the normalized spatial median can perform more efficiently than the normalized mean in presence of ...
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作者：DOLBY, GR; CORMACK, RM; SINCLAIR, DF
作者单位：University of St Andrews; Commonwealth Scientific & Industrial Research Organisation (CSIRO)
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作者：LIANG, KY
作者单位：Imperial College London
摘要：A locally most powerful test is proposed for homogeneity of nuisance parameters from many strata in the mixed model setting. The test is based on the difference between the square of the score and the observed information about the nuisance parameters, all evaluated at the null hypothesis. Several examples including constant normal mean with possibly different variances and matched case-control studies are presented in detail. The relative efficiencies of the unstratified estimator of paramete...
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作者：MATTHEWS, JNS
摘要：A model for responses in a crossover experiment that includes direct and first-order carryover treatment effects, together with an autocorrelated error term, is considered when there are two treatments. A method for generating designs that minimize the variance of the estimated treatment effects is proposed and explicit results are given for the three and four period cases. Efficiencies of some practical designs are calculated.
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作者：PIGEON, JG; RAGHAVARAO, D
作者单位：Merck & Company; Pennsylvania Commonwealth System of Higher Education (PCSHE); Temple University
摘要：We introduce a class of crossover designs with residual effects for experimental situations in which primary interest centres on the comparison of several test treatments. We shall call these designs ''control balanced residual effects designs''. Their structure is studied in detail, some methods of their construction are given and their relative efficiencies are evaluated.
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作者：KIM, K; DEMETS, DL
摘要：Lan and DeMets (1983) devised a method for constructing discrete group sequential boundaries by using the type I error spending rate function. It is extended so as to generate asymmetric as well as symmetric two-sided boundaries for clinical trials. The design aspect of this procedure is explored in terms of the maximum sample size needed to achieve a desired level of power and the expected stopping times under both null and alternative hypotheses. Finally, these properties are employed in sea...
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作者：JOE, H
作者单位：University of British Columbia
摘要：Given independent and identically distributed random variables from an unknown distribution F, we want to estimate quantiles of FN. Using asymptotic extreme-value theory, two parametric approximations to FN are considered and approximate maximum likelihood estimates are obtained. Conditions for consistency and asymptotic normality of these estimates are given, and properties of the estimates are obtained through a small simulation study.
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作者：RAAB, GM; YU, JZ
摘要：The consistent least-squares estimator, proposed by Jewell (1985) for linear regression with data arising from stratified samples, lacks invariance with respect to a change of location of the dependent variable. Simulation suggests that its efficiency is reduced when the origin of the dependent variable is far from its mean. This estimator can be made invariant to a change of location by specifying that the dependent variable is measured from the estimated population mean. Another similar inva...
