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11.
本文以改革后的苏北的一所县级重点中学为个案,以围绕高三教师名单公布的升级事件为切入点,从组织的微观视角出发,描述在升级事件中的教师在各种情境下如何利用手头的已有资源来展开行动的策略,并在游戏各方的行动中构建出一个特有的组织权力结构。 相似文献
12.
13.
本文借助“权力的文化网络”视角,深层再现云南省一个少数民族山区--蚌岚河槽(村庄)传统主族控制和毕摩操控的村落政治格局。作者认为,1949年以前槽区的社会政治局面是主族控制和毕摩操控,主族及其首领毕摩依靠乡村文化网络获得权威和认受性,他们在权力的文化网络中发挥着组织领导的作用,凭借对乡村文化网络(族群内部的宗族关系和宗教信仰以及族群关系等)的操控,主族及其首领毕摩有力地控制着乡村社会。 相似文献
14.
In this paper we examine maximum likelihood estimation procedures in multilevel models for two level nesting structures. Usually,
for fixed effects and variance components estimation, level-one error terms and random effects are assumed to be normally
distributed. Nevertheless, in some circumstances this assumption might not be realistic, especially as concerns random effects.
Thus we assume for random effects the family of multivariate exponential power distributions (MEP); subsequently, by means
of Monte Carlo simulation procedures, we study robustness of maximum likelihood estimators under normal assumption when, actually,
random effects are MEP distributed. 相似文献
15.
Marschner IC 《Pharmaceutical statistics》2007,6(1):23-33
Clinical trials are often designed to compare several treatments with a common control arm in pairwise fashion. In this paper we study optimal designs for such studies, based on minimizing the total number of patients required to achieve a given level of power. A common approach when designing studies to compare several treatments with a control is to achieve the desired power for each individual pairwise treatment comparison. However, it is often more appropriate to characterize power in terms of the family of null hypotheses being tested, and to control the probability of rejecting all, or alternatively any, of these individual hypotheses. While all approaches lead to unbalanced designs with more patients allocated to the control arm, it is found that the optimal design and required number of patients can vary substantially depending on the chosen characterization of power. The methods make allowance for both continuous and binary outcomes and are illustrated with reference to two clinical trials, one involving multiple doses compared to placebo and the other involving combination therapy compared to mono-therapies. In one example a 55% reduction in sample size is achieved through an optimal design combined with the appropriate characterization of power. 相似文献
16.
Chang M 《Pharmaceutical statistics》2007,6(1):43-52
Multiple-arm dose-response superiority trials are widely studied for continuous and binary endpoints, while non-inferiority designs have been studied recently in two-arm trials. In this paper, a unified asymptotic formulation of a sample size calculation for k-arm (k>0) trials with different endpoints (continuous, binary and survival endpoints) is derived for both superiority and non-inferiority designs. The proposed method covers the sample size calculation for single-arm and k-arm (k> or =2) designs with survival endpoints, which has not been covered in the statistic literature. A simple, closed form for power and sample size calculations is derived from a contrast test. Application examples are provided. The effect of the contrasts on the power is discussed, and a SAS program for sample size calculation is provided and ready to use. 相似文献
17.
摘 要:理论研究表明许多经济变量呈现出非对称的门限自回归(TAR)或动态门限自回归(M-TAR)数据生成机制,因而非对称单位根检验就成为该领域的主要研究方向之一。本文对非对称单位根检验Enders-Granger方法在GARCH(1,1)-正态误差项下的检验水平与检验势作了系统的仿真研究。研究表明:GARCH(1,1)-正态误差项的TAR或M-TAR模型会对该方法的检验水平和检验势产生重要影响。 相似文献
18.
Wolfgang Kössler 《Statistical Papers》1999,40(1):13-35
The two-sample scale problem is studied in the case of unequal and unknown location parameters. The method proposed is based on the idea of Moses (1963) and it is distribution-free. The two samples are separated into random subgroups of the same sizek. It is proposed to choosek=4 and to apply the Wilconxon test or the Savage test to the ranges or sample variances of the subgroups. The asymptotic power functions of the tests are compared. For small and moderate sample sizes simulations are carried out. Relations to some other procedures, especially to the method of Compagnone and Denker (1996) are briefly discussed. 相似文献
19.
G = F
k
(k > 1); G = 1 − (1−F)
k
(k < 1); G = F
k
(k < 1); and G = 1 − (1−F)
k
(k > 1), where F and G are two continuous cumulative distribution functions. If an optimal precedence test (one with the maximal power) is determined
for one of these four classes, the optimal tests for the other classes of alternatives can be derived. Application of this
is given using the results of Lin and Sukhatme (1992) who derived the best precedence test for testing the null hypothesis
that the lifetimes of two types of items on test have the same distibution. The test has maximum power for fixed κ in the
class of alternatives G = 1 − (1−F)
k
, with k < 1. Best precedence tests for the other three classes of Lehmann-type alternatives are derived using their results. Finally,
a comparison of precedence tests with Wilcoxon's two-sample test is presented.
Received: February 22, 1999; revised version: June 7, 2000 相似文献
20.
We propose an efficient group sequential monitoring rule for clinical trials. At each interim analysis both efficacy and futility are evaluated through a specified loss structure together with the predicted power. The proposed design is robust to a wide range of priors, and achieves the specified power with a saving of sample size compared to existing adaptive designs. A method is also proposed to obtain a reduced-bias estimator of treatment difference for the proposed design. The new approaches hold great potential for efficiently selecting a more effective treatment in comparative trials. Operating characteristics are evaluated and compared with other group sequential designs in empirical studies. An example is provided to illustrate the application of the method. 相似文献