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随机比较研究中估计处理效应的稳健 ANCOVA 替代方法AI 解读

In comparing two treatments via a randomized clinical trial, the analysis of covariance (ANCOVA) technique is often utilized to estimate an overall treatment effect. The ANCOVA is generally perceived as a more efficient procedure than its simple two sample estimation counterpart. Unfortunately, when the ANCOVA model is nonlinear, the resulting estimator is generally not consistent. Recently, various nonparametric alternatives to the ANCOVA, such as the augmentation methods,…

为未来比较研究有效选择目标人群AI 解读

When comparing a new treatment with a control in a randomized clinical study, the treatment effect is generally assessed by evaluating a summary measure over a specific study population. The success of the trial heavily depends on the choice of such a population. In this paper, we show a systematic, effective way to identify a promising population, for which the new treatment is expected to have a desired benefit, utilizing the data from a current study involving similar…

观测与删失时间依赖协变量的面板计数数据回归分析AI 解读

Summary Panel count data often occur in a long-term study where the primary end point is the time to a specific event and each subject may experience multiple recurrences of this event. Furthermore, suppose that it is not feasible to keep subjects under observation continuously and the numbers of recurrences for each subject are only recorded at several distinct time points over the study period. Moreover, the set of observation times may vary from subject to subject. In…

依赖删失重复测量下治疗差异的秩估计AI 解读

In comparing the effectiveness of two treatments, suppose that for each patient repeated measurements of an outcome variable are taken at prespecified time points, but some observations may be missing due to the patient's dependent right censoring. In this article, a simple rank estimation procedure, constructed based on an artificial censoring technique, is proposed for the treatment differences over time without imposing a parametric structure on the dependence between the…

依赖删失下基于重复测量的治疗差异秩估计AI 解读

In comparing the effectiveness of two treatments, suppose that for each patient repeated measurements of an outcome variable are taken at prespecified time points, but some observations may be missing due to the patient's dependent right censoring. In this article, a simple rank estimation procedure, constructed based on an artificial censoring technique, is proposed for the treatment differences over time without imposing a parametric structure on the dependence between the…

基于中位数回归模型的生存分析AI 解读

The median is a simple and meaningful measure for the center of a long-tailed survival distribution. To examine the covariate effects on survival, a natural alternative to the usual mean regression model is to regress the median of the failure time variable or a transformation thereof on the covariates. In this article we propose semiparametric procedures to make inferences for such median regression models with possibly censored observations. Our proposals can be…

基于枢轴估计函数的重抽样方法AI 解读

Suppose that, under a semiparametric model setting, one is interested in drawing inferences about a finite-dimensional parameter vector β based on an estimating function. Generally a consistent point estimator β^ for βo, the true value for β, can be easily obtained by finding a root of the corresponding estimating equation. To estimate the variance of β^, however, may involve complicated and subjective nonparametric functional estimates. In this paper, a general and simple…

基于枢轴估计函数的重抽样方法AI 解读

SUMMARY Suppose that, under a semiparametric model setting, one is interested in drawing inferences about a finite-dimensi onal parameter vector /? based on an estimating function. Generally a consistent point estimator /J for /?0, the true value for /J, can be easily obtained by finding a root of the corresponding estimating equation. To estimate the variance of ft, however, may involve complicated and subjective nonparametric functional estimates. In this paper, a general…

基于中位生存时间的期中分析AI 解读

For a typical two-arm survival study, analyses are usually performed periodically to evaluate, for example, the treatment difference. In this paper, we propose to use differences or ratios of estimated median survival times repeatedly during a study to evaluate the relative merit of two treatment groups. This new procedure provides quantitative assessments of the treatment difference and is completely model-free. Our method is illustrated with a recent aids clinical study…

多元失效时间观测的线性回归分析AI 解读

In this article we consider the case that each patient in a longitudinal study may experience two or more distinct failures. The corresponding failure times, which are possible censored, are recorded for each patient. The logarithm of each marginal failure time is assumed to be linearly related to its covariates; however, the distributional form of the error term in the model does not have to be specified in the analysis. Furthermore, no specific structure of dependence…

数据依赖型治疗分配规则下的统计推断AI 解读

In comparing two treatments with dichotomous responses, the randomized play-the-winner rule (Wei and Durham 1978) tends to assign more study subjects to the better treatment. For ethical reasons, this property is desirable for studies on human subjects. The randomized play-the-winner rule, which is a modification of Zelen's play-the-winner rule (Zelen 1969), is not deterministic and is less vulnerable to experimental bias than other adaptive designs. Recently, this design…

受限随机分配规则下的区间估计AI 解读

In comparing two treatments in a clinical trial, suppose that patients are assigned sequentially to treatments by a restricted randomization rule. Exact and approximate confidence intervals for treatment difference are derived without assuming that the study subjects were obtained by random sampling from a well-defined population. We show that, if there is a time trend among the responses of study subjects, one should not ignore the design in the analysis. All the procedures…

受限随机分配规则下的区间估计AI 解读

In comparing two treatments in a clinical trial, suppose that patients are assigned sequentially to treatments by a restricted randomization rule. Exact and approximate confidence intervals for treatment difference are derived without assuming that the study subjects were obtained by random sampling from a well-defined population. We show that, if there is a time trend among the responses of study subjects, one should not ignore the design in the analysis. All the procedures…

临床试验中受限随机化规则下的多处理比较AI 解读

In the course of conducting a clinical trial to compare $K (\geq 2)$ treatments, it is often desirable to balance the trial with respect to the assignments of patients to treatments. On the other hand, some form of randomization of treatment assignments is essential for reducing experimental bias. In this article, the large-sample approximation to the null distribution of $K$-sample randomization tests generated from a broad class of restricted randomization rules is…

不完整多元观测的两样本渐近分布无关检验AI 解读

Asymptotically distribution-free tests for equality of two multivariate distributions based on censored observations are proposed. By choosing appropriate test scores, we obtain the multivariate versions of the Gehan and log-rank tests. An important application of the proposed tests is in the area in which multiple observations are collected on study subjects, some of whom may have missing observations. The patterns of missing observations are allowed to differ for the two…

受限随机化设计下的显著性检验AI 解读

Experimental subjects are assigned to one of two treatments sequentially by restricted randomization assignment rules. Significance tests generated from these rules are discussed. Under rather mild conditions on the test scores the asymptotic null permutational distribution of tests based on the urn design (Wei, 1977, 1978a) is shown to be normal.

受限随机化设计下的显著性检验AI 解读

Experimental subjects are assigned to one of two treatments sequentially by restricted randomization assignment rules. Significance tests generated from these rules are discussed. Under rather mild conditions on the test scores the asymptotic null permutational distribution of tests based on the urn design (Wei, 1977, 1978a) is shown to be normal.

摘要暂缺

随机完全区组设计中处理差异的渐近分布无关同时置信域AI 解读

Summary For a randomized complete block design with additive block effects, an asymptotically distribution-free simultaneous confidence region of pairwise treatment differences is presented. The corresponding confidence bound has an explicit form and is easily obtained. Asymptotic relative efficiency comparisons with other known confidence regions are made to show the advantage of the proposed procedure. The case of treatment against control is also discussed.

瓮模型在序贯对照临床试验设计中的应用AI 解读

In the comparison of K treatments, assume that patients appear singly and must be treated immediately. Suppose that patients having the same combination of prognostic factor levels are grouped into the same stratum. If the number of different strata is small, we treat each stratum as a separate independent subtrial. A treatment assignment rule is proposed that forces a small subtrial to be balanced, but tends toward the complete randomization scheme as the size of the…

序贯实验的自适应偏币设计AI 解读

In comparing two treatments, eligible subjects come to the experiment sequentially and must be treated at once. To reduce experimental bias and to increase the precision of inference about treatment effects, the adaptive biased coin design, which offers a compromise between perfect balance and complete randomization, is proposed and analyzed. This new design has the property that it forces a small-sized experiment to be balanced, but tends toward the complete randomization…

序贯实验中控制选择偏差的随机分配设计AI 解读

In comparing two treatments, suppose that eligible subjects come to the experiment sequentially and must be treated immediately. In this paper we assume that the experimenter selects 2n subjects and treat n subjects with each treatment. If, during the experiment, the experimenter knows or guesses which treatment is to be administered next, he may bias the experiment by his selection of subjects. The problem is how to control this bias through choice of design. In this paper,…