中国人口容量与适度人口问题研究

:本文回顾了我国学术界对我国人口容量和适度人口问题的研究 ,就人口容量研究的意义、人口容量的概念、研究方法、对我国人口容量的估算和有待进一步研究的问题等进行了概括与总结。人口容量的科学研究是一件极为复杂和困难的事情 ,既取决于自然科学和社会科学有待认识的过程 ,也取决于我们和子孙后代有待作出的选择。     

Smallholder land ownership in Kenya: distribution between households and through time

This study uses panel data to demonstrate two dimensions of land ownership: the distribution between households at a given time and changes within a household over time. We note that recognizing the latter dimension is only possible when analyzing rare long‐term panel data. We estimate a model for land ownership using a version of the correlated random effects estimator to uniquely identify the determinants of both dimensions amongst Kenyan smallholders. We find life cycle effects are a key determinant of both distributions, and identify important ways in which initial conditions such as inheritance and off‐farm income relate to the dynamics of ownership. We find that population density is a key determinant of differences between households, but also that a given household's land ownership is not affected in the short term as population density increases around them. Controlling for population density, households own more land when they are closer to road networks where the economic value of land is higher. We find important vulnerabilities for the land security of widows, but this vulnerability is geographically heterogeneous.     

人口普查中遗漏人口数的估计

研究目标:用完整遗漏估计量替代目前使用的未匹配遗漏估计量、逆记录检查遗漏估计量和平衡推算遗漏估计量。研究方法:采取文献解读、成果借鉴和移植及实地调查相结合的方法,研究完整遗漏估计量及其方差估计。研究发现:人口普查遗漏估计不只是要提供遗漏估计值,还要揭示遗漏的原因及其遗漏者的特征;构造普查遗漏估计量,既要包括登记在事后计数调查人口名单而未登记在普查名单的单重遗漏人口,还要包括同时遗漏于这两项调查名单的双重遗漏人口。研究创新:提出完整遗漏估计量。研究价值:完整遗漏估计量有望应用于中国2030年普查遗漏估计,开创世界人口普查遗漏估计应用完整遗漏估计量的先河。     

Patterns of growth in Chinese cities: Implications of the land lease

A special feature of China’s housing market is land use rights in the form of land leasehold contracts granted by the government. We consider an equilibrium model in which a representative developer may choose to redevelop existing centrally located housing or to develop new housing at the periphery of the city. We show that as the city grows, the land leasehold system results in the city center being developed less intensely and more land being used on the outskirts of the city when compared to a fee simple environment. Thus, cities in China are likely to be relatively more spread out, with city centers relatively older than would be the case with “fee simple” ownership. Our model suggests that excess residential land use is about 6 percent. In addition, compared with the ownership case, housing supply will grow more quickly in the near future, but more slowly later on during the transition of the Chinese economy. Parallel to the supply growth pattern, equilibrium price grows relative slowly in the near future, but more quickly later on. While we focus on residential uses, we believe our model can be applied to other land uses.     

Decomposing the growth in residential land in the United States

This paper decomposes the growth in land occupied by residences in the United States to give the relative contributions of changing demographics versus changes in residential land per household. Between 1976 and 1992 the amount of residential land in the United States grew 47.7% while population only grew 17.8%. At first glance, this suggest an important role for per-household increases. However, the calculations in this paper show that only 24.5% of the growth in residential land area can be attributed to state-level changes in land per household. 37.3% is due to overall population growth, 22.6% to an increase in the number of households over this period, 6% to the shift of population towards states with larger houses, and the remaining 9.6% to interactions between these changes. There are large differences across states and metropolitan areas in the relative importance of these components.     

Time-varying road network design for urban hazmat transportation

Hazmat transportation in cities faces significant risks that may cause catastrophic losses to humans. From the perspective of the regulator, the main responsibility is to mitigate hazmat transport risk by determining the availability of road networks to hazmat carriers. Based on the time-variant population distribution, the hazmat transport risk was assessed via the total population exposure associated with the resident and variable populations at different times. We propose a risk-minimizing urban hazmat road network design model for multiple types of hazmats, considering time-varying traffic. The model was applied to a realistic case study of hazmat transportation in a densely populated urban area with complex traffic in Shanghai, China.     

Land pressures,the evolution of farming systems,and development strategies in Africa: A synthesis

Evidence assembled in this special issue of Food Policy shows that rising rural population densities in parts of Africa are profoundly affecting farming systems and the region’s economies in ways that are underappreciated in current discourse on African development issues. This study synthesizes how people, markets and governments are responding to rising land pressures in Africa, drawing on key findings from the various contributions in this special issue. The papers herein revisit the issue of Boserupian agricultural intensification as an important response to land constraints, but they also go further than Boserup and her followers to explore broader responses to land constraints, including non-farm diversification, migration, and reduced fertility rates. Agricultural and rural development strategies in the region will need to more fully anticipate the implications of Africa’s rapidly changing land and demographic situation, and the immense challenges that mounting land pressures pose in the context of current evidence of unsustainable agricultural intensification, a rapidly rising labor force associated with the region’s current demographic conditions, and limited nonfarm job creation. These challenges are manageable but will require explicit policy actions to address the unique development challenges in densely populated rural areas.     

中国人口城镇化的省级行政单元差异分析

基于周一星修正的1982—2000年城镇化数据和2005年全国1%人口抽样调查数据,本文依据所构建的人口城镇化贡献模型,以省级行政单元为基本研究对象,考察了1982—2005年研究期内不同时段省级行政单元的人口城镇化差异变动情况。主要从城镇人口的相对增长指数和城镇人口增长的贡献率这两个方面来分析各省级行政单元的城镇化差异,按时段将之落实到地图上,并将所有的省级行政单元划分成三个类型,然后将其对应于人口城镇化进程的四个阶段。最后,简单地说明了各省级行政单元在人口城镇化进程中四种类型的转换过程或阶段转变。     

Simpler Probabilistic Population Forecasts: Making Scenarios Work

The traditional high-low-medium scenario approach to quantifying uncertainty in population forecasts has been criticized as lacking probabilistic meaning and consistency. This paper shows, under certain assumptions, how appropriately calibrated scenarios can be used to approximate the uncertainty intervals on future population size and age structure obtained with fully stochastic forecasts. As many forecasting organizations already produce scenarios and because dealing with them is familiar territory, the methods presented here offer an attractive intermediate position between probabilistically inconsistent scenario analysis and fully stochastic forecasts.