中国的城市化与人口迁移——2000年以来的实证研究

内容提要：以中国统计年鉴、中国城市统计年鉴和全国经济与社会发展统计公报中的相关数据为依据,分析了中国2000年以来城市化及人口迁移的特征。从全国整体上看：2000年以来,中国的城市化水平增长速度较快,但有减缓的趋势;新增城镇人口和农村-城镇净迁入人口规模仍然较大,但都趋于递减,且净迁入人口对城市人口增长的贡献率也在下降。从城市层面上看：城市规模越大,对迁移人口的吸引力、净迁移人口对城市人口增长的贡献就越大;东、西部城市的净迁入率、净迁入人口对城市人口增长的贡献率都大于中部城市。进一步在分析其成因的基础上提出了相应的政策建议。     

经济、管理类专业《统计学》课程建设的几个基本问题

内容提要：本人认为,目前在我国经济、管理类专业《统计学》课程建设中尚有一些基本理论问题需要讨论清楚。例如,怎样理解“统计学是一门数据科学”这一命题,以及课程改革后的《统计学》与改革前的《社会经济统计学原理》究竟有什么本质上的区别;《统计学》课程中用于对重复随机试验进行统计推断的样本和抽样调查中的样本有什么区别和联系;应用社会经济调查数据进行统计分析较之应用实验数据进行统计分析有什么特殊性的问题需要解决,等等。文章找出了这些问题的若干误区并阐述了作者的个人见解。     

内生性人口负增长经济影响的国际比较北大核心CSSCI

由长期低生育率和老龄化导致的内生性人口负增长是未来人口发展的新趋势。这种崭新的人口现象改变了人口研究的宏观环境,也引发了人们对未来经济能否实现持续发展的普遍担忧。本文使用联合国2019年世界人口展望数据和世界银行数据,筛选出德国、俄罗斯、匈牙利、波黑、立陶宛、日本作为典型的人口负增长国家,以人口缩减比例作为人口负增长风险的度量指标,以各国持续时间最久的一次负增长时域作为考察范围,从国别队列视角和生命周期思想出发,利用同原点比较模型系统考察典型国家在人口负增长之后的经济增长、劳动参与率变化、固定资产变化和技术进步情况,探索人口负增长风险积累程度对社会经济的影响。结果发现:各典型国家的人口负增长无论持续时间长短、速度快慢,其经济在最长负增长时域内均尚未出现明显的衰退;人口负增长对劳动参与率的影响并不明显,各国劳动参与率整体上在稳定范围内波动;人口负增长对固定资本形成占GDP比重和技术进步的影响方向各异,尚未显示出统一规律。人口负增长对宏观经济指标的影响是多种效应的合力,不是单向度的,充满了不确定性和异质性。尽管国际经验如此,未来中国将在“未富先负”的背景下迎来“快负快老”,仍需要未雨绸缪,谨慎应对。     

A probabilistic transmission and population dynamic model to assess tuberculosis infection risk

The purpose of this study was to examine tuberculosis (TB) population dynamics and to assess potential infection risk in Taiwan. A well‐established mathematical model of TB transmission built on previous models was adopted to study the potential impact of TB transmission. A probabilistic risk model was also developed to estimate site‐specific risks of developing disease soon after recent primary infection, exogenous reinfection, or through endogenous reactivation (latently infected TB) among Taiwan regions. Here, we showed that the proportion of endogenous reactivation (53–67%) was larger than that of exogenous reinfection (32–47%). Our simulations showed that as epidemic reaches a steady state, age distribution of cases would finally shift toward older age groups dominated by latently infected TB cases as a result of endogenous reactivation. A comparison of age‐weighted TB incidence data with our model simulation output with 95% credible intervals revealed that the predictions were in an apparent agreement with observed data. The median value of overall basic reproduction number (R₀) in eastern Taiwan ranged from 1.65 to 1.72, whereas northern Taiwan had the lowest R₀ estimate of 1.50. We found that total TB incidences in eastern Taiwan had 25–27% probabilities of total proportion of infected population exceeding 90%, whereas there were 36–66% probabilities having exceeded 20% of total proportion of infected population attributed to latently infected TB. We suggested that our Taiwan‐based analysis can be extended to the context of developing countries, where TB remains a substantial cause of elderly morbidity and mortality.     

Reduced-Variance Methods for Detectability Correction of Population Abundance

Detectability issues create uncertainty in field surveys of animal and plant populations. Detectability correction is one method employed to deal with this problem when there is reasonable certainty that detectability is roughly constant with time or in different areas. Two new reduced-variance estimators of detectability are introduced and evaluated for the case of using a detectability correction for new areas that are surveyed only once. The new estimates are unbiased or nearly unbiased and produce population estimates with smaller variance than the Lincoln–Petersen estimate.     

Admissibility of a variance estimator in finite population sampling under Warner's randomized response plan with multiple responses

ABSTRACT

Let P be the proportion of individuals in a finite population possessing a sensitive attribute. We consider the problem of unbiased estimation of (i) the variance of a linear unbiased estimator of P and (ii) the population variance P (1—P) for a given probability sampling design under Warner's (1965 Warner, S.L. (1965). Randomized response - A survey technique for eliminating evasive answer bias. J. Amer. Statist. Assoc. 60:63–69.[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) randomized response (RR) plan when independent responses are obtained from each sampled individual as many times as he/she is selected in the sample and prove the admissibility of a quadratic unbiased estimator for each.     

Simple Formulae for Evaluating the Potential Impact of Confounding Bias

Unmeasured confounding is a common problem in observational studies. This article presents simple formulae that can set the bounds of the confounding risk ratio under three standard populations of the exposed, unexposed, and total groups. The bounds are derived by considering the confounding risk ratio as a function of the prevalence of a covariate, and can be constructed using only information about either the exposure–confounder or the disease–confounder relationship. The formulae can be extended to the confounding odds ratio in case–control studies, and the confounding risk difference is discussed. The application of these formulae is demonstrated using an example in which estimation may suffer from bias due to population stratification. The formulae can help to provide a realistic picture of the potential impact of bias due to confounding.     

Some improved ratio type estimators of population mean and ratio in finite population sample surveys

In this paper we present a class of ratio type estimators of the population mean and ratio in a finite population sample surveys with without replacement simple random sampling design, where information on an auxiliary variate x positively correlated with the main variate y is available. Large sample approximations to mean square errors (MSE) of these estimatorsare evaluated and their MSE's are compared with the MSE of the usual ratio estimator [ybar]_R of [ybar] the population mean of y. It is shown that under certain conditions these estimators are more efficient than [ybar]_R. When a prior knowledge of the value of thecoefficient of variation, c_y, of y is at hand, ratio type estimator, say [ybar]₁ of [ybar] is proposed. It is shown, under certain conditions, that [ybar]₁ is more efficient than [ybar]_R. When values of c_y, c_x and the population correlation coefficient ρ is at hand, then we have proposed another estimator, say [ybar]₂ of [ybar], which is always better than [ybar]_R as far as the efficiency is concerned. In fact, is [ybar] ₂ is shown to be even better than [ybar]₁. Finally estimators better than the usual ratio estimator [ybar]/[xbar] of [Ybar] are given.     

用动态子结构的加权残数法计算电站锅炉炉墙动力特性

本文利用动态子结构的加权残数法来计算大型电站锅炉炉墙的动力特性,使计算时处理的自由度数远小于有限元法,输入数据的总量大幅度下降,而其计算精度则与用大型通用有限元程序SAP5近于相同。     

剧变中的我国留守妻子及其学术与公共政策含义

针对被广泛使用的“留守妇女冶概念的歧义,文章首先提出了“留守妻子冶概念。 2000 年以来全国人口普查和 1% 人口抽样调查资料揭示,我国留守妻子在进入 21 世纪后发生了一系列重大变化:其规模由剧增到快速减少,农村留守妻子的规模减少更早更快,留守妻子的来源地构成正在经历快速城镇化,留守妻子的居住方式类型构成正在快速直系化等。 这些变化有着重要的学术研究和公共政策含义。