The relationship between the length of the base period and population forecast errors

"The base period of a population forecast is the time period from which historical data are collected for the purpose of forecasting future population values. The length of the base period is one of the fundamental decisions made in preparing population forecasts, yet very few studies have investigated the effects of this decision on population forecast errors. In this article the relationship between the length of the base period and population forecast errors is analyzed, using three simple forecasting techniques and data from 1900 to 1980 for states in the United States. It is found that increasing the length of the base period up to 10 years improves forecast accuracy, but that further increases generally have little additional effect. The only exception to this finding is long-range forecasts of rapidly growing states, in which a longer base period substantially improves forecast accuracy for two of the forecasting techniques."     

The Effects of Variations in the Components of Change on the Size and Structure of The Australian Population: 1911-66

The main aim of the study was to estimate separately the effects of the variations in the components of population change and the effects of their mutual interactions on the size and age structure and other characteristics of the Australian population during 1911-66. The method proposed, called here the factorial projection method, is to project the population over the period under consideration, under different assumptions according to a 2×2×2 factorial design, utilizing the observed variations in fertility, mortality and migration. It was found that, apart from the effects of variations in the components occurring individually, the two factor interaction effects– the interaction effects of the changes occurring simultaneously in two of the components (viz. fertility and mortality or mortality and migration or fertility and migration)–on the population size, were considerable. The contribution of migration to the working age group was greater than its effect on the total size, and mortality improvement played a more prominent role in increasing the size of the old age population, while the reduction in fertility caused a higher proportion in the old age group and thus increased the mean age of the population both in the case of males and females. The two factor interaction effects were not negligible in changing the size of the school age population, population in the working age group and also in the old age group. But the interaction of migration and the decline in fertility was the only interaction effect which was important in changing the percentage age distribution and the mean age of the male and female population.     

人口空间分布及迁移影响的实证分析——基于空间计量方法与河南省数据

在传统研究方法的基础上考虑空间相关性,运用空间计量经济学的理论与方法,并以河南省人口数据为例进行人口空间分布及迁移的实证研究。一方面,研究中运用全域空间性和局域空间性的相关知识分析河南省人口空间分布,通过定量性指标的运用得出河南省人口空间分布存在相关性,且是高值集聚,即人口密度较高的地区集中在一起;另一方面,在考虑空间相关性的基础上建立空间计量模型,主要研究各个政府支出对河南省人口迁移和分布的影响,结果发现各支出的影响显著。     

A method of computing the marital composition of the population between population censuses

A method for calculating the marital status distribution of the population of the USSR between censuses is outlined. The method is based on the use of population census and vital statistics data.     

Construction of Confidence Intervals for the IVIean of a Population Containing Many Zero Values

The likelihood ratio method is used to construct a confidence interval for a population mean when sampling from a population with certain characteristics found in many applications, such as auditing. Specifically, a sample taken from this type of population usually consists of a very large number of zero values, plus a small number of nonzero values that follow some continuous distribution. In this situation, the traditional confidence interval constructed for the population mean is known to be unreliable. This article derives confidence intervals based on the likelihood-ratio-test approach by assuming (1) a normal distribution (normal algorithm) and (2) an exponential distribution (exponential algorithm). Because the error population distribution is usually unknown, it is important to study the robustness of the proposed procedures. We perform an extensive simulation study to compare the percentage of confidence intervals containing the true population mean using the two proposed algorithms with the percentage obtained from the traditional method based on the central limit theorem. It is shown that the normal algorithm is the most robust procedure against many different distributional error assumptions.     

A population of 40 million in Poland in the year 2000

Poland's population is projected to reach 40 million by the year 2000. In connection with this, the author compares Poland's position among other nations in Europe in terms of population size. The analysis further concentrates on various characteristics of the population.     

Unbiased estimation of the parameter of a selected binomial population

The problem is to estimate the parameter of a selected binomial population. The selction rule is to choose the population with the greatest number of successes and, in the case of a tie, to follow one of two schemes: either choose the population with the smallest index or randomize among the tied populations. Since no unbiased estimator exists in the above case, we employ a second stage of sampling and take additional observations on the selected population. We find the uniformly minimum variance unbiased estimator (UMVUE) under the first tie break scheme and we prove that no UMVUE exists under the second. We find an unbiased estimator with desirable properties in the case where no UMVUE exists.     

不同城市的房价是否具有相同的人口集聚效应——基于35个大中城市PVAR模型的实证分析

人口集聚会引起房价上涨,但不同类型的城市由于集聚人口的教育程度不同,房价上涨也具有不同的效应。首先建立人口流动理论模型分析人口集聚对房价上涨的影响,然后通过建立房价、人口集聚、房地产投资和人均可支配收入的PVAR模型进行实证分析。结论表明,一类城市人口集聚对房价上涨具有正效应,二类城市为平效应,三类城市为负效应;三类城市的房价上涨主要是房地产投资和人均收入提高所推动的。     

On the distribution of the correlation coefficient when sampling from a mixture of two bivariate normal densities: Robustness and the effect of outliers

The distribution of the sample correlation coefficient is derived when the population is a mixture of two bivariate normal distributions with zero mean but different covariances and mixing proportions 1 - λ and λ respectively; λ will be called the proportion of contamination. The test of ρ = 0 based on Student's t, Fisher's z, arcsine, or Ruben's transformation is shown numerically to be nonrobust when λ, the proportion of contamination, lies between 0.05 and 0.50 and the contaminated population has 9 times the variance of the standard (bivariate normal) population. These tests are also sensitive to the presence of outliers.     

Demographic policy in the light of the resolutions of the Twenty-sixth Congress of the Communist Party

The USSR is moving from extensive to intensive type of population reproduction, not because of any governmental measures but as a reaction to objective circumstances. At present there is a reduction in the population cohort of working age. This has an adverse effect on production. And the number of the elderly is increasing; we must involve them more in the production process, in monitoring the service sphere, for instance. The infant mortality rate has declined sharply in the USSR, especially since World War II. The birthrate has also dropped, but it is still higher than in the US, France, or West Germany. Some authorities think that this (the ZPG) is a good idea, but this author thinks it is a bad idea, meaning a drop in society's productive forces. We need an active demographic policy, meaning one which ensures optimal reproduction of the population with an improvement in its health, culture, and living standard. The policy must be differentiated, as conditions vary from one part of the country to another. An example is the 1981 decree on assistance to families with children which provides for payments of 35-50 rubles/month to mothers who must stay home to look after children. The number of children per family to ensure reproduction must be 2.6 on the average. In the Central Asian republics family sizes of 4-5 children are anticipated, but in the RSFSR, Ukraine, Belorussia, and the Baltic republics the anticipated size of families is rather low. Measures must be taken to alter this by providing assistance to families with children.     

关于人口统计调查方法体系存在的问题和改革设想

我国现行的人口统计调查方法体系是“以经常性的人口抽样调查为主体,以人口普查为基础,重点调查等为补充的多种方法的运用”,但随着经济社会的快速发展,“以普查为基础,经常性抽样调查为主体"的人口统计调查方法体系,与政府、社会对人口信息多层次、精细化、时效性的需求变得不适应,在实践中显露出矛盾和问题。本文以下将对当前人口普查和人口变动情况抽样调查,在人口统计中作用和存在问题做出分析,在此基础上提出人口统计的改革设想,并落实到具体的解决办法,以2020年第七次人口普查为契机,建立《人口统计与管理服务数据平台》,并结合社区网格化管理进行年度更新,取得年度全国、省级及省级以下的常住人口数据;同时改革人口抽样调查的内容,结合手机信令大数据在人口统计中的应用,完善人口统计调查方法体系。     

Estimating and contextualizing the attenuation of odds ratios due to non collapsibility

The odds ratio is a measure commonly used for expressing the association between an exposure and a binary outcome. A feature of the odds ratio is that its value depends on the choice of the distribution over which the probabilities in the odds ratio are evaluated. In particular, this means that an odds ratio conditional on a covariate may have a different value from an odds ratio marginal on the covariate, even if the covariate is not associated with the exposure (not a confounder). We define the individual odds ratio (IORs) and population odds ratios (PORs) as the ratio of the odds of the outcome for a unit increase in the exposure, respectively, for an individual in the population and for the whole population, in which case the odds are averaged across the population. The attenuation of conditional odds ratio, marginal odds ratio, and PORs from the IOR is demonstrated in a realistic simulation exercise. The degree of attenuation differs in the whole population and in a case–control sample, and the property of invariance to outcome-dependent sampling is only true for the IOR. The relevance of the non collapsibility of odds ratios in a range of methodological areas is discussed.     

中国城镇化的地域非均衡及其动态演进——来自基尼系数及核密度估计的经验证据

基于中国1995-2013年省域数据,采用基尼系数及其分解、核密度估计方法,从人口和土地城镇化入手,系统分析了中国城镇化的地域非均衡及其动态演化规律。结果发现,1.中国人口和土地城镇化分布均呈现出由东往西逐渐降低的规律,城镇化非均衡主要体现在土地城镇化,而人口城镇化则未出现明显分异。2.全国尺度人口城镇化基尼系数随时间不断下降,城镇化非均衡逐渐减小;土地城镇化基尼系数则呈倒"U"型,城镇化非均衡先增后减。3.东中西三大区域内人口城镇化基尼系数均呈直线下降,区域间非均衡东部最大,西部次之,中部最小;土地城镇化非均衡则是东部大于中部和西部,但近年来西部已超过东部。4.人口城镇化非均衡在1995-2001年间主要来自地区间重叠,而后2002-2013年主要由地区间差异驱动;土地城镇化非均衡则主要来源于地区间差异。5.核密度估计显示人口城镇化增速较快,波动较小,而土地城镇化则极化趋势明显,波动较大。新型城镇化的协调推进宜从人口和土地城镇化两方面着手,特别要注意土地城镇化的失衡发展问题。     

Measurement and analysis of demographic processes: the characteristics of generation

Since it would take too long (100 years) to ascertain all demographic data about a given age group, i.e., all those born in a given year, these data are determined hypothetically by measuring the various characteristics of persons of all ages in a given time period (1-2 years). Also needed is an indicator of the population as a whole; cumulative coefficients are used for this purpose. One of these is the overall coefficient of births, meaning the number of children a women would have over her whole period of fertility if she had the precise number of children at each period in her life as other women of that age. An analogous indicator is used for measuring mortality--the average life expectancy of a person at each stage in his life. The crude coefficient of population reproduction represents the number of girls to which each woman will give birth between the ages of 15 and 50. This has to be corrected by the number of those who will not live to reproductive age. The result is the corrected coefficient of reproduction of the female population. This coefficient is often thought to reflect the population's growth prospects; if less than unity, therefore, the population will not reproduce itself. This is an incorrect interpretation. The impact of immigration and emigration on the population must also be incorportated. In addition to the above hypothetical indicators, we must also develop real population indicators. Techniques must also be employed to evaluate the reliability of these demographic indicators.     

Subset selection of the best treatment via many-one tests

The method of Gupta (1956, 1965) was developed to select a subset from k normal populations that contains the best populations with given probability. This paper shows a duality between the general goal of selecting a subset for the best population and many-one tests. A population should be regarded as ‘candidate’ for the best population and thus retained in the subset if the samples from the other populations are not significantly better. Based on this ‘idea’ a general selection procedure is proposed using many-one tests for the comparison of each population against the remaining ones.     

The use of resighting data to estimate the rate of population growth of the snail kite in Florida

The rate of population growth ( u ) is an important demographic parameter used to assess the viability of a population and to develop management and conservation agendas. We examined the use of resighting data to estimate u for the snail kite population in Florida from 1997-2000. The analyses consisted of (1) a robust design approach that derives an estimate of u from estimates of population size and (2) the Pradel (1996) temporal symmetry (TSM) approach that directly estimates u using an open-population capture-recapture model. Besides resighting data, both approaches required information on the number of unmarked individuals that were sighted during the sampling periods. The point estimates of u differed between the robust design and TSM approaches, but the 95% confidence intervals overlapped substantially. We believe the differences may be the result of sparse data and do not indicate the inappropriateness of either modelling technique. We focused on the results of the robust design because this approach provided estimates for all study years. Variation among these estimates was smaller than levels of variation among ad hoc estimates based on previously reported index statistics. We recommend that u of snail kites be estimated using capture-resighting methods rather than ad hoc counts.     

基于行政记录人口普查方法的国际比较

开展基于行政记录的人口普查被视为有效破解传统人口普查难题的途径之一,亦是顺应大数据时代充分挖掘人口行政记录资源的必然之选。本文较系统地阐述了基于行政记录人口普查方法的基本框架,尝试对“完全模式”人口普查和“组合模式”人口普查的实施步骤进行解析。基于此,本文选择芬兰、奥地利、瑞士、荷兰四个国家,分普查基本情况、行政记录类型选择和基本记录库形成、已存在统计记录系统基本结构、专门组织的抽样调查设计、不同系统间的链接途径、新人口统计信息质量评估方法等六个维度,对实施基于行政记录的人口普查方法进行了国家比较。     

Anticipated demographic development in Poland in the light of the new demographic projections

The authors present the results of revised population projections for Poland for 1985 based on the final results of the 1978 population census. Assumptions made in previous projections are critically reviewed, as are the population estimates on which those projections were based     

Test of two hypotheses explaining the size of populations in a system of cities

Two classical hypotheses are examined about the population growth in a system of cities: Hypothesis 1 pertains to Gibrat's and Zipf's theory which states that the city growth–decay process is size independent; Hypothesis 2 pertains to the so-called Yule process which states that the growth of populations in cities happens when (i) the distribution of the city population initial size obeys a log-normal function, (ii) the growth of the settlements follows a stochastic process. The basis for the test is some official data on Bulgarian cities at various times. This system was chosen because (i) Bulgaria is a country for which one does not expect biased theoretical conditions; (ii) the city populations were determined rather precisely. The present results show that: (i) the population size growth of the Bulgarian cities is size dependent, whence Hypothesis 1 is not confirmed for Bulgaria; (ii) the population size growth of Bulgarian cities can be described by a double Pareto log-normal distribution, whence Hypothesis 2 is valid for the Bulgarian city system. It is expected that this fine study brings some information and light on other usually considered to be more pertinent countries of city systems.     

A new class of unbiased estimators of the variance of the systematic sample mean

We propose a class of estimators of the variance of the systematic sample mean, which is unbiased under the assumption that the population follows a superpopulation model that satisfies some mild conditions. The approach is based on the separate estimation of the portion of the variance due to the systematic component of the model and that due to the stochastic component. In particular, we deal with two estimators belonging to the proposed class that are based on moving averages and local polynomials to estimate the systematic component of the model. The latter estimators are unbiased under the assumption that the population follows a linear trend and the errors are homoscedastic and uncorrelated. Through a simulation study we show that these estimators generally outperform, in terms of bias and mean square error, the usual estimator based on the first differences also when the superpopulation model departs significantly from linearity and the errors are heteroscedastic.