公共政策执行应当承受之重

公共政策的价值能否实现或其能够实现的效度,在很大程度上取决于执行。公共政策是一个因变量,其执行要受到各种执行资源包括政治、经济、技术等条件的可获得性,执行者的价值、利益关系与能力,政策受众的认可程度等在内的多种变量的影响制约。当代社会信念与利益的过度分散性加剧了执行的难度。自1970年代初政策执行研究勃兴以来,学界对政策执行所进行的多视角多层面的研究,从理论与实践的结合上极大地推进了这一新兴领域的发展。在经济社会转型时期的中国,由于种种原因公共政策的执行会面临更多的变数。因此,需要特别关注和深入研究公共政策执行所须应对的挑战,以利于政策价值的实现。     

A Test for Independence of Competing Risks with Discrete Failure Times

The identifiability problem in Competing Risks is well known. In particular, it implies that independent action or otherwise of the risks cannot be inferred from data alone. However, Crowder (1996) showed that, in the case of purely discrete failure times, an inference can be made. An algebraic criterion was derived which bears essentially on the independence in question. The condition was presented in a theoretical setting but it was pointed out that the quantities involved can be estimated from data and that, therefore, there is the potential to develop practical tests for the hypothesis of independence. It is the purpose of this paper to construct such a test. This revised version was published online in July 2006 with corrections to the Cover Date.     

政府在现代市场经济中的职能

以“外部性”为核心的天然缺陷使市场失灵在所难免,政府行为的“内部性”又使政府实施的是私人或集团的目标,寻租行为从而产生,进而出现了政府失灵。现代市场经济的政府调节是第二次调节,是更高层次的调节,是总体上、全局上的调节。其作用应以公共物品提供为主。随着知识时代的到来,更需要政府加强其追求扩大公共利益的倾向,推动共同利益群体的产生。     

尤索林与“二十二条军规”的搏斗

尤索林生活的世界是一个极权主义的世界。它的象征物──第二十二条军规，给尤索林的生在造成了永久的威胁，尤索林在认识到这一点之后，绝望地发起了一场针对第二十二条军规以及它所代表的极权制度的单枪匹马的斗争。但他本性软弱，缺乏大胆反叛的勇气，因此他的反抗只是些荒诞的举止。这表明一个无足轻重的小人物反极权制度的反抗注定是要失败的。     

Dealing with Ties in Failure Time Data

In dealing with ties in failure time data the mechanism by which the data are observed should be considered. If the data are discrete, the process is relatively simple and is determined by what is actually observed. With continuous data, ties are not supposed to occur, but they do because the data are grouped into intervals (even if only rounding intervals). In this case there is actually a non–identifiability problem which can only be resolved by modelling the process. Various reasonable modelling assumptions are investigated in this paper. They lead to better ways of dealing with ties between observed failure times and censoring times of different individuals. The current practice is to assume that the censoring times occur after all the failures with which they are tied.     

Assessing gamma frailty models for clustered failure time data

Proportional hazards frailty models use a random effect, so called frailty, to construct association for clustered failure time data. It is customary to assume that the random frailty follows a gamma distribution. In this paper, we propose a graphical method for assessing adequacy of the proportional hazards frailty models. In particular, we focus on the assessment of the gamma distribution assumption for the frailties. We calculate the average of the posterior expected frailties at several followup time points and compare it at these time points to 1, the known mean frailty. Large discrepancies indicate lack of fit. To aid in assessing the goodness of fit, we derive and estimate the standard error of the mean of the posterior expected frailties at each time point examined. We give an example to illustrate the proposed methodology and perform sensitivity analysis by simulations.     

修理延迟的n部件串联系统的可靠性分析

在部件寿命服从指数分布,延迟修理时间和修理时间均服从一般分布的假设下,研究了修理延迟的n部件串联的可修系统。利用更新过程理论,得到了系统的可靠度R(t)、可用度A、首次故障前的平均时间MTTFF和(0,t]时间内的系统的平均故障次数M(t)等可靠性指标。     

Bartlett's Test Applied to Variance Component Models

Exact methods for testing equality between variance components obtained from several cases of the same type of balanced orthogonal design are discussed. In particular, methods for successively testing equality of a number of components using Bartlett's tests are outlined for univariate and multivariate responses. Two clinical trial examples of repeated‐measures data are presented.     

Statistical Modelling and Deconvolution of Yield Meter Data

Abstract.  This paper considers the problem of mapping spatial variation of yield in a field using data from a yield monitoring system on a combine harvester. The unobserved yield is assumed to be a Gaussian random field and the yield monitoring system data is modelled as a convolution of the yield and an impulse response function. This results in an unusual spatial covariance structure (depending on the driving pattern of the combine harvester) for the yield monitoring system data. Parameters of the impulse response function and the spatial covariance function of the yield are estimated using maximum likelihood methods. The fitted model is assessed using certain empirical directional covariograms and the yield is finally predicted using the inferred statistical model.     

Using Graph Models to Analyze the Vulnerability of Electric Power Networks

In this article, we model electric power delivery networks as graphs, and conduct studies of two power transmission grids, i.e., the Nordic and the western states (U.S.) transmission grid. We calculate values of topological (structural) characteristics of the networks and compare their error and attack tolerance (structural vulnerability), i.e., their performance when vertices are removed, with two frequently used theoretical reference networks (the Erdös‐Rényi random graph and the Barabási‐Albert scale‐free network). Further, we perform a structural vulnerability analysis of a fictitious electric power network with simple structure. In this analysis, different strategies to decrease the vulnerability of the system are evaluated. Finally, we present a discussion on the practical applicability of graph modeling.