A bias analysis of Weibull models under heaped data

Retrospectively collected duration data are often reported incorrectly. An important type of such an error is heaping—respondents tend to round-off or round-up the data according to some rule of thumb. For two special cases of the Weibull model we study the behaviour of the ‘naive estimators’, which simply ignore the measurement error due to heaping, and derive closed expressions for the asymptotic bias. These results give a formal justification of empirical evidence and simulation-based findings reported in the literature. Additionally, situations where a remarkable bias has to be expected can be identified, and an exact bias correction can be performed.     

三峡地区近代交通史略(一)

中国进入近代以后,三峡地区的交通发展处于一个特定的历史时期。西方列强的入侵、军阀之间的混战、民族解放战争的开展、社会矛盾和民族矛盾的深化等,都对三峡交通的发展产生了深远的影响。     

学生视野:高校大课堂教学中值得注意的几个问题

采用无记名方式对实施学分制的本科生大课堂教学现状作了调查。调查结果显示大课堂教学中存在着诸如讲授方法、教学媒介、逃课现象以及学生主体地位缺失等问题,并就此进行了深入、多层面的分析,希望引起相关部门的重视,使学生在学分制改革中普遍受益。     

Semiparametric Time-Varying Coefficients Regression Model for Longitudinal Data

Abstract.  In this paper, we consider a semiparametric time-varying coefficients regression model where the influences of some covariates vary non-parametrically with time while the effects of the remaining covariates follow certain parametric functions of time. The weighted least squares type estimators for the unknown parameters of the parametric coefficient functions as well as the estimators for the non-parametric coefficient functions are developed. We show that the kernel smoothing that avoids modelling of the sampling times is asymptotically more efficient than a single nearest neighbour smoothing that depends on the estimation of the sampling model. The asymptotic optimal bandwidth is also derived. A hypothesis testing procedure is proposed to test whether some covariate effects follow certain parametric forms. Simulation studies are conducted to compare the finite sample performances of the kernel neighbourhood smoothing and the single nearest neighbour smoothing and to check the empirical sizes and powers of the proposed testing procedures. An application to a data set from an AIDS clinical trial study is provided for illustration.     

近年来毛泽东民主政治思想研究综述

毛泽东民主政治思想是目前学术界关注的重大课题,学界近年来对这一课题进行了较全面的研究,大体来说,学界的研究主要围绕以下几方面进行：对毛泽东民主政治思想的主要内容进行概括；对毛泽东民主政治思想的重大论题进行分析；对毛泽东民主政治思想与社会主义政治文明的关系进行探讨；对毛泽东、邓小平的民主政治思想进行比较；对毛泽东晚年民主政治思想及其实践失误原因进行探析。学者的研究成果显著,但仍存在较大的研究空间。     

目前中国网络调查的局限性和适用范围

网络调查的逐渐兴起和蓬勃发展,使人大有传统调查过时之感,也有人认为网络调查将很快取代传统的数据收集方法。但网络调查毕竟是一种新生事物,其方法的科学性如何?结果的有效性、准确性怎样?实践中有哪些新的理论问题需要探讨?等等,目前还没有一套完整的理论加以阐述。本文拟就     

Survey nonresponse and the distribution of income

The paper examines the distributional implications of selective compliance in sample surveys, whereby households with different incomes are not equally likely to participate. Poverty and inequality measurement implications are discussed for monotonically decreasing and inverted-U compliance-income relationships. We demonstrate that the latent income effect on the probability of compliance can be estimated from information on response rates across geographic areas. On implementing the method on the Current Population Survey for the U.S. we find that the compliance probability falls monotonically as income rises. Correcting for nonresponse appreciably increases mean income and inequality, but has only a small impact on poverty incidence up to poverty lines common in the U.S. Martin Ravallion: Corresponding author.     

清末各省调查局和修订法律馆的习惯调查

作为新政期间法制改革活动的重要组成部分,清末的习惯调查是国家政权在立法实践中对本土资源进行全面整理利用的一次巨大尝试。调查是在宪政编查馆和修订法律馆的管理下分别进行的。民商事习惯调查是清末习惯调查的一部分。清末的习惯调查尽管规模巨大,但在组织管理上缺乏协调一致。受限于清末预备立宪的时代背景,其在发挥为修订和审核法律的参考作用方面十分有限。     

改革高校课外体育活动的管理——以浙海院课外体育活动现状调查分析为例

通过高校部分大学生参加课外体育活动现状的调查,对高校学生参加课外体育活动的认知、活动空间结构特点、场地器材使用和课外体育活动组织及内容进行理性分析,提出高校课外体育活动组织管理的原则和方法.     

Perfect samplers for mixtures of distributions

Summary. We consider the construction of perfect samplers for posterior distributions associated with mixtures of exponential families and conjugate priors, starting with a perfect slice sampler in the spirit of Mira and co-workers. The methods rely on a marginalization akin to Rao–Blackwellization and illustrate the duality principle of Diebolt and Robert. A first approximation embeds the finite support distribution on the latent variables within a continuous support distribution that is easier to simulate by slice sampling, but we later demonstrate that the approximation can be very poor. We conclude by showing that an alternative perfect sampler based on a single backward chain can be constructed. This alternative can handle much larger sample sizes than the slice sampler first proposed.