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比较实验与小区域估计中的贝叶斯及非贝叶斯程序：计算、频率学性质与联系AI 解读

The estimation of a treatment contrast from experimental data and the estimation of a small-area mean are special cases of the prediction of the realization of a linear combination of fixed and random effects in a possibly unbalanced two-part mixed linear model. In this article a Bayesian approach to point and interval prediction is presented and its computational requirements are examined. Differences between the Bayesian approach and the traditional (classical) approach…

乘法强度模型中对数秩检验的相对效率AI 解读

For large-sample clinical trials with independent individuals randomly allocated to two treatment groups, in which survival times follow a log linear multiplicative intensity model with treatment group as one covariate, this paper calculates the asymptotic relative efficiency of the log rank test for treatment effect as compared with the optimal score test. The method is to exhibit the failure hazard intensity, not of proportional hazards form, obtained by ignoring all…

多元分析中处理效应与误差的条件推断AI 解读

Directional methods of conditional inference are applied to the multivariate analysis of variance. Exact and easily implemented tests are derived for treatment effect, error variance matrix, and treatment improvement. Each test provides a physical measure of the magnitude of the departure from expectation under the hypothesis and is conditional on the indicated direction of departure. For treatment effect the test provides a geometrically understandable alternative to tests…

有偏处理分配下乘法处理效应的估计AI 解读

Suppose that, given θ, x is Poisson with mean θ, while, given θ, y is Poisson with mean αθ or βθ according as treatment 1 or treatment 2 is used. Moreover, suppose that treatment 1 is used if x < a, while treatment 2 is used if x≥ a. Under this biased allocation of treatments we give consistent estimators of the two treatment effects α and β. The method also applies when x is binomial and θ is the odds on success, and to other cases.

通过比较调查与支出数据检验官僚对地方学校支出的影响AI 解读

Previous empirical studies of bureaucratic power have employed testing procedures that are sensitive only to complete bureaucratic power in which the bureaucrat is able to force an all or nothing choice on his legislative sponsor. This paper suggests a test for incomplete bureaucratic power in which micro-based, survey estimates of the cost elasticity of demand and marginal propensity to spend out of lump-sum aid are compared with estimates of these same parameters taken…

重度删失数据下处理效应的一般估计量AI 解读

A generalized Hodges-Lehmann type estimator for the treatment effect in the two-sample problem with right censoring, is proposed based on an inverse-quantile-type idea using truncated versions of the Kaplan-Meier estimators over the subspace where they are consistent. Its strong consistency and asymptotic normality can be obtained, under no conditions on the uninformative censorings, and the resulting variance is easily estimable from the data. In simulation studies the…

多元分析中处理效应与误差的条件推断AI 解读

Directional methods of conditional inference are applied to the multivariate analysis of variance. Exact and easily implemented tests are derived for treatment effect, error variance matrix, and treatment improvement. Each test provides a physical measure of the magnitude of the departure from expectation under the hypothesis and is conditional on the indicated direction of departure. For treatment effect the test provides a geometrically understandable alternative to tests…

乘法强度模型中对数秩检验的相对效率AI 解读

SUMMARY For large-sample clinical trials with independent individuals randomly allocated to two treatment groups, in which survival times follow a log linear multiplicative intensity model with treatment group as one covariate, this paper calculates the asymptotic relative efficiency of the log rank test for treatment effect as compared with the optimal score test. The method is to exhibit the failure hazard intensity, not of proportional hazards form, obtained by ignoring…

有偏治疗分配下的乘法治疗效应估计AI 解读

Suppose that, given θ, x is Poisson with mean θ, while, given θ, y is Poisson with mean αθ or βθ according as treatment 1 or treatment 2 is used. Moreover, suppose that treatment 1 is used if x < a, while treatment 2 is used if x≥ a. Under this biased allocation of treatments we give consistent estimators of the two treatment effects α and β. The method also applies when x is binomial and θ is the odds on success, and to other cases.

线性模型中对比方差的估计AI 解读

A common problem in the reporting of statistical analyses is the presentation of standard errors of nonindependent effects. In particular, it is desirable to provide a useful indication of the covariance structure of the parameter estimates. The problem is considered for several cases. First, in an analysis of covariance situation, we derive upper and lower bounds for the standard error of an arbitrary linear contrast of treatment effects; the method allows for unequal…

关于 Wei 临床试验偏置硬币设计的统计推断AI 解读

Wei (1988) analyzed data from a clinical trial in which an urn-sampling model was used to allocate patients to treatments. The trial resulted in 11 patients being allocated to the experimental treatment, all successes, and with one patient allocated to the control treatment, a failure. Wei analyzed these data using a randomization algorithm and concluded that the results were almost significant at p = 0·051. He asserted that an analysis which ignored the design and presumed…

重复测量设计中区组间秩统计量的效率AI 解读

For factorial designs, tests that rely on the method of n rankings, for example, the Friedman test, suffer a potential loss of power since they depend only on within-block ranks. This deficiency is overcome by ranking across blocks as is done in the aligned rank tests and the rank transform procedures. This article examines a broad class of powerful interblock rank statistics for testing for both treatment effects and ordered alternatives and for performing multiple…

观察性研究中双样本置换推断的敏感性AI 解读

In observational studies, subjects are not randomly assigned to treatment or control, so they may differ in their chances of receiving the treatment. A simple method is developed and demonstrated for displaying the sensitivity of conventional two-group permutation inferences to departures from random assignment of treatments. The unmatched case, discussed here, differs in certain technical and computational details from the matched case, discussed previously; however, the…

观察性研究中两样本置换推断的敏感性AI 解读

In observational studies, subjects are not randomly assigned to treatment or control, so they may differ in their chances of receiving the treatment. A simple method is developed and demonstrated for displaying the sensitivity of conventional two-group permutation inferences to departures from random assignment of treatments. The unmatched case, discussed here, differs in certain technical and computational details from the matched case, discussed previously; however, the…

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…

债券储架注册与自选择偏误AI 解读

Prior studies report lower issue costs for shelf registered debt and conclude that the benefits of increased underwriter competition can be realized by those firms using this registration procedure. This study reexamines the purported superiority of issuing debt via shelf registration, and finds that the savings in issue costs displayed by earlier studies can be attributed to a self-selection bias and not the method of registration. Copyright 1990 by American Finance…

债务储架注册与自选择偏差AI 解读

ABSTRACT Prior studies report lower issue costs for shelf registered debt and conclude that the benefits of increased underwriter competition can be realized by those firms using this registration procedure. This study re‐examines the purported superiority of issuing debt via shelf registration, and finds that the savings in issue costs displayed by earlier studies can be attributed to a self selection bias and not the method of registration.

从前测到后测的数据流失：一个样本选择问题AI 解读

When estimating regression models of educational achievement with pre- and posttest data, researchers have overlooked a sample selection bias that may occur even where initial assignment to the control and experimental groups is random. The bias arises because students who take the pretest but do not take the posttest are excluded from the regression analysis. Using data from a nationally normed test of high school student knowledge of economics, adjustment for this bias is…

关于 Wei 临床试验偏置硬币设计的统计推断AI 解读

Wei (1988) analyzed data from a clinical trial in which an urn-sampling model was used to allocate patients to treatments. The trial resulted in 11 patients being allocated to the experimental treatment, all successes, and with one patient allocated to the control treatment, a failure. Wei analyzed these data using a randomization algorithm and concluded that the results were almost significant at p = 0·051. He asserted that an analysis which ignored the design and presumed…

序贯临床试验结束后的治疗差异估计AI 解读

To reduce the number of patients needed to reach a conclusion in a clinical trial, a sequential trial design may be used. In theory the distribution of responses is biased when a sequential trial is stopped. The usual estimation methods of treatment difference applied in nonsequential situations are, therefore, not necessarily applicable following a sequential test. Whitehead (1983) proposed a method for estimating the treatment effect following some types of two-sample…

序贯临床试验结束后的治疗差异估计AI 解读

To reduce the number of patients needed to reach a conclusion in a clinical trial, a sequential trial design may be used. In theory the distribution of responses is biased when a sequential trial is stopped. The usual estimation methods of treatment difference applied in nonsequential situations are, therefore, not necessarily applicable following a sequential test. Whitehead (1983) proposed a method for estimating the treatment effect following some types of two-sample…

观察性研究中隐蔽偏差的置换检验：Holley 不等式与 Savage 格AI 解读

Randomized experiments and observational studies both attempt to estimate the effects produced by a treatment, but in observational studies, subjects are not randomly assigned to treatment or control. A theory of observational studies would closely resemble the theory for randomized experiments in all but one critical respect: In observational studies, the distribution of treatment assignments is not known. The problems that are special to observational studies revolve…

实验随机化与正态理论推断的有效性AI 解读

This article examines how randomization helps to validate model-based probability statements. The asymptotic validity of normal-theory tests for means in multivariate linear models is established under general conditions. Numerical results are presented showing how randomization provides a limited degree of robustness in small experiments. The conditional relevance of randomization is also discussed. Consider the following additive model for a comparative experiment: Y = θ +…

非参数政策分析AI 解读

This article considers the problem of predicting the mean effect of a change in the distribution of certain policy-related variables on a dependent variable (Y). This is conventionally done using a parametric model. If, however, the conditional expectation of Y, given policy and nonpolicy variables X, is unaltered by the policy intervention, and if the support of X after the policy intervention lies within the support of X before the intervention, then this analysis can be…