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结果依赖两阶段抽样下半参数回归的大样本理论AI 解读

Outcome-dependent, two-phase sampling designs can dramatically reduce the costs of observational studies by judicious selection of the most informative subjects for purposes of detailed covariate measurement. Here we derive asymptotic information bounds and the form of the efficient score and influence functions for the semiparametric regression models studied by Lawless, Kalbfleisch and Wild (1999) under two-phase sampling designs. We show that the maximum likelihood…

过度离散泊松回归及其他拟似然模型中的假设检验AI 解读

Test statistics for evaluating the significance of added variables in a regression equation are developed for mixed Poisson models, where the structural parameter φ that determines the mean/variance relationship var(μ; φ) = μ + φ · μ 2 is estimated by the method of moments and the regression coefficients are estimated by quasi-likelihood. The formulas presented for test statistics and related estimating equations are applicable generally to quasi-likelihood models specified…

稀疏数据下的优势比估计量AI 解读

The properties of four commonly used estimators of the odds ratio are studied under a large-sample scheme in which the number of 2 × 2 tables increases but the possible marginal configurations remain fixed. Neither the unconditional maximum likelihood nor the empirical logit estimators converge to the true odds ratio; their asymptotic bias is computed for certain special cases of interest. The conditional maximum likelihood and Mantel-Haenszel estimators, which are…

稀疏数据下的优势比估计量AI 解读

The properties of four commonly used estimators of the odds ratio are studied under a large-sample scheme in which the number of 2 × 2 tables increases but the possible marginal configurations remain fixed. Neither the unconditional maximum likelihood nor the empirical logit estimators converge to the true odds ratio; their asymptotic bias is computed for certain special cases of interest. The conditional maximum likelihood and Mantel-Haenszel estimators, which are…

指数生存曲线的序贯比较AI 解读

A general approach is outlined to the problem of sequentially comparing exponential “survival” curves in a clinical trials setting. It entails applying sequential tests of hypotheses concerning the drift of a Wiener process to a particular discrete-time process generated from the survival data. Anderson's [1] modified sequential probability ratio test [SPRT) is used for illustration. Monte Carlo studies indicate that the method is valid for samples of moderate size and that…

指数生存曲线的序贯比较AI 解读

A general approach is outlined to the problem of sequentially comparing exponential “survival” curves in a clinical trials setting. It entails applying sequential tests of hypotheses concerning the drift of a Wiener process to a particular discrete-time process generated from the survival data. Anderson's [1] modified sequential probability ratio test [SPRT) is used for illustration. Monte Carlo studies indicate that the method is valid for samples of moderate size and that…

二项概率一致最强检验的序贯修改AI 解读

The early decision version of the uniformly most powerful (UMP) fixed-sample-size test for binomial probabilities, as described for instance by Alling [1], is modified by changing all continuation points which lie on or below a line with specified slope into acceptance points. The modification reduces the average sample number (ASN) for small values of the binomial probability with only a slight loss of power. Approximate formulas for the ASN and power function of the…

二项概率一致最强检验的序贯修改AI 解读

The early decision version of the uniformly most powerful (UMP) fixed-sample-size test for binomial probabilities, as described for instance by Alling [1], is modified by changing all continuation points which lie on or below a line with specified slope into acceptance points. The modification reduces the average sample number (ASN) for small values of the binomial probability with only a slight loss of power. Approximate formulas for the ASN and power function of the…

不同删失模式下比较K个样本的广义Kruskal–Wallis检验AI 解读

A generalization of the Kruskal-Wallis test, which extends Gehan's generalization of Wilcoxon's test, is proposed for testing the equality of K continuous distribution functions when observations are subject to arbitrary right censorship. The distribution of the censoring variables is allowed to differ for different populations. An alternative statistic is proposed for use when the censoring distributions may be assumed equal. These statistics have asymptotic chi-squared…