Population dynamics in Germany: the role of immigration and population momentum

The effects of changes in rates of mortality, fertility, and migration depend not only on the age-specific patterns and levels of these rates, but on the age structure of the population. In order to remove the influences of the age structure and concentrate on the effects of the demographic rates themselves, a common practice is to analyze the influences of the rates for a standard age structure. This paper analyzes current and future population changes in Germany, using a stationary population equivalent model (SPE) that shows long-term effects of current fertility, mortality, and international migration patterns. Results indicate that the German population will eventually decline because of below replacement fertility, if net immigration does not counteract this decrease. This means, for instance, that the long-term stationary population levels for Germany will decrease by approximately 6.5 million during a decade in which current fertility, mortality, and international migration levels prevail. The paper also reports how various other assumptions for mortality, fertility, and international migration affect the SPE model for Germany.     

Population and Climate Change: Consensus and Dissensus among Demographers

What role does population play in thinking about the problem of climate change and some of its solutions? In a survey conducted between February and April 2020, we asked European demographers to state their views on the relationship between climate change and population developments, and asked them to rate their concern about climate change and other socio-demographic issues. We found that climate change is at the top of the list of demographers’ concerns, but that their sense of urgency with respect to taking action to redress global warming is not matched by their belief that population policy can make a crucial difference in reducing CO₂ emissions: demographers are highly divided on the question whether the global population size should be reduced to lower CO₂ emissions, as well as on the question whether family planning is an effective policy instrument.     

鼓励生育政策能否提高生育率?——基于生育成本缺口递增的视角

中国总和生育率的下降引发调整生育政策的讨论,但鲜有对鼓励生育政策的效果评估与理论解释.通过马斯洛需求层次理论构建生育成本缺口递增假说,并基于世界人口政策数据库与OECD家庭数据库对基于转移支付的鼓励生育政策进行了效果评估,得出如下结论:第一,生育成本是一种动态结构,需求跃迁导致生育成本缺口增速快于收入增速,进而决定鼓励...     

A SINGLE CHANNEL ON/OFF MODEL WITH TCP-LIKE CONTROL

We model behavior of a TCP-like source transmitting over a single channel to a server that processes work at a constant rate τ. Transmission by the source follows an on/off mechanism. When the overall load in the system is below a critical constant γ, transmission rates increase linearly but when the load exceeds γ, then transmission rates decrease geometrically fast. We study the system by means of an embedded Markov chain, which gives the buffer content at the start of transmissions. Attention is paid to the time necessary to transmit a file of size L and both the tail behavior and expectation of the distribution of file transmission time are considered.     

An alternative approach for analysis of performance of one-sided cusum charts with variable sampling intervals

An alternative approach for analyzing performance of one-sided Cusum charts with variable sampling intervals (VSI) is proposed. In this approach, a Markov chain with some dummy states is used. By this approach some dynamic performance measures of the VSI Cusum charts, such as the distribution of time to signal and the average time to signal against a change-point, can be determined. Some numerical results are shown, and from these results the dynamic performance of VSI Cusum charts is discussed.     

CUSUM Chart with Transformed Exponential Data

Time Between Events (TBE) charts were proposed to monitor the time between events occur based on exponential distribution, and have been shown to be more effective than monitoring the fraction non conforming directly. In this article, we consider monitoring the TBE data with CUSUM scheme by transformation. The idea behind it is to transform the TBE data to normal, and then apply the CUSUM scheme for the approximate normal data. Several simple transformation methods are examined. The calculation of Average Run Length (ARL) with Markov chain approach is described. Comparative studies on the ARL performance show that the transformed CUSUM is superior to the X-MR (Moving Range) chart with transformation, the Cumulative Quantity Control (CQC) chart, and have comparable performance with exponential CUSUM charts. The design procedures of optimal CUSUM chart are also presented. This study provides another possible alternative for monitoring TBE data with easy design procedures and relatively good performance.     

Exponentially smoothed control charts for the inverse-gaussian process

Exponential smoothing technique is used to obtain centrality and dispersion control charts for an Inverse-Gaussian(IG)process. The centrality and dispersion control charts use linear combinations of IG and chi-square random variables, respectively. Simulation results are used to verify the approximate distribution of the linear combinations. A method for choosing the “best” value for the weighting constant is presented. An example illustrates the computations that are involved in finding the control limits.     

Improved Shewhart-type Runs-rules Nonparametric Sign Charts

Runs-rules are typically incorporated in control charts to increase their sensitivity to detect small process shifts. However, a drawback of this approach is that runs-rules charts are unable to detect large shifts quickly. In this article improved runs-rules are introduced to the nonparametric sign chart to address this limitation. Improved runs-rules are incorporated to maintain sensitivity to small process shifts, while having the added ability to detect large shifts in the process more efficiently. Performance comparisons between sign charts with runs-rules and sign charts with improved runs-rules illustrate that the improved runs-rules are superior in performance for large shifts in the process, while maintaining the same sensitivity in the detection of small shifts.     

中国人口出生控制成效的比较分析

中国 ①的计划生育工作起始于 2 0世纪 5 0年代。从 1 95 5年到 1 971年 ,中国推行的是一般性的家庭计划生育政策 ,从 1 971年至今 ,中国推行的是家庭计划生育与国家计划生育相结合的政策。如果不实行任何形式的计划生育政策 ,2 0 0 0年末中国人口将会达到 1 8 5 8亿 ,如果象印度那样只倡导自愿实行家庭计划生育 ,将会达到 1 5 3 2亿。过去 45年中 ,中国一共少生了 5 88亿人 ,其中由于实行国家计划生育政策少生了 2 6 2亿人 ,而一般性的家庭计划生育政策少生了 3 2 6亿人。计划生育为中国的社会经济发展做出了巨大的贡献     

千名育龄人群生育意愿的调查与分析

根据2002年8月在湖南省进行的一项育龄人群生育意愿调查,本文分析了人们生育意愿的一些变化特点,并就如何更加有力地引导人们生育意愿的健康变化提出一些建议。