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作者：SAMIUDDIN, M; ELSAYYAD, GM
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作者：COX, DR; WERMUTH, N
作者单位：Johannes Gutenberg University of Mainz
摘要：An approximation to the maximum likelihood estimates of the parameters in a model can be obtained from the corresponding estimates and information matrices in an extended model, i.e. a model with additional parameters. The approximation is close provided that the data are consistent with the first model. Applications are described to log linear models for discrete data, to models for multivariate normal distributions with special covariance matrices and to mixed discrete-continuous models.
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作者：ZUCKER, DM; LAKATOS, E
摘要：In certain long-term treatment trials, one expects some lag period before the treatment is fully effective. This paper presents two weighted log rank type statistics designed to have good efficiency over a wide range of lags: a maximum efficiency robust statistic and a simplified version of this statistic. Both statistics can be computed as easily as the log rank statistic. Asymptotic efficiency calculations, supported by small sample simulations, show that the two proposed statistics are subs...
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作者：LANGHOLZ, B; THOMAS, D; CHEN, TJ; RHODES, P
作者单位：Centers for Disease Control & Prevention - USA
摘要：A test of an effect in matched case-control studies, natural in an analysis of variance context, compares within matched set case-control mean differences to the within matched set variances after removing the case-control effect. For large odds ratios, heuritis reasoning suggests that this new test should be more powerful than the standard score test when two or more controls are matched to any case. Asymptotic theory confirms this in some important situations. Simulation results reveal, howe...
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作者：YING, ZL
摘要：Motivated by Prentice''s (1978) generalization of linear rank statistics for censored data, we introduce a similar kernal for deriving linear rank statistics or truncated data. They take very similar forms to those of Prentice''s statistics. Moreover, we also show that they can be expressed equivalently in weighted log rank-type forms, thus providing natural variance estimators. Explicit forms corresponding to Wilcoxon and log rank tests are obtained. Extensions to data subject to both left tr...
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作者：GOWER, JC
摘要：The biplot of a two-way table is discussed as a diagnostic tool for investigating bilinear models with additive terms for rows and columns and at least one multiplicative term. The full biplot is three dimensional with the points representing row effects concentrated in a plane orthogonal to another plane containing the points representing the column effects. Projections onto suitable directions in these planes give the row, column and multiplicative constants of the model. Extensions to more ...
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作者：BERMAN, SM
摘要：A mathematical model is proposed for the description of the T4 level, as a function of the time since initial infection, in the blood of an HIV-infected individual. Two random variables are defined for each infected individual, the time T from the moment of infection to the moment when the infection is first discovered, and the level R of T4 cells in the blood at the time of the discovery. Here T is the length of the latency period, and is not typically observable. On the basis of a stochastic...
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作者：HOOVER, DR; GUESS, FM
作者单位：Johns Hopkins University; University of Tennessee System; University of Tennessee Knoxville
摘要：A form of positive dependence between censoring time and response time is defined as response linked, RL, censoring. We present a method for modelling, estimation and detection of RL censoring in situations where both RL and independent censoring can occur. This method involves parametric modelling with covariates and is illustrated with the Stanford heart transplant data. Other applications are mentioned.
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作者：JONES, RH; ACKERSON, LM
作者单位：National Jewish Health
摘要：Serial correlation in the within subject error structure in longitudinal data with unequally spaced observations is modelled using continuous time autoregressive moving averages. The models considered have both fixed and random effects in addition to serially correlated within subject errors. Two approaches are presented for calculating the exact likelihood for a model when the errors are Gaussian. The first calculates the covariance matrices for each subject for assumed values of the unknown ...
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作者：EMERSON, SS; FLEMING, TR
作者单位：University of Washington; University of Washington Seattle
摘要：Parameter estimation techniques which fail to adjust for the interim analyses of group sequential test designs will introduce bias in much the same way that the repeated use of single sample hypothesis testing causes inflation of the type one statistical error rate. Methods based on the duality of hypothesis testing and interval estimation require definition of an ordering for the outcome space for the test statistic. In this paper, estimation following a group sequential hypothesis test for t...
