Population projection

Abstract: The future paths of population ageing result from specific combinations of declining fertility and increasing life expectancies in different parts of the world. Here we measure the speed of population ageing by using conventional measures and new ones that take changes in longevity into account for the world as a whole and for 13 major regions. We report on future levels of indicators of ageing and the speed at which they change. We show how these depend on whether changes in life expectancy are taken into account. We also show that the speed of ageing is likely to increase over the coming decades and to decelerate in most regions by mid-century. All our measures indicate a continuous ageing of the world's population throughout the century. The median age of the world's population increases from 26.6 years in 2000 to 37.3 years in 2050 and then to 45.6 years in 2100, when it is not adjusted for longevity increase. When increases in life expectancy are taken into account, the adjusted median age rises from 26.6 in 2000 to 31.1 in 2050 and only to 32.9 in 2100, slightly less than what it was in the China region in 2005. There are large differences in the regional patterns of ageing. In North America, the median age adjusted for life expectancy change falls throughout almost the entire century, whereas the conventional median age increases significantly. Our assessment of trends in ageing is based on new probabilistic population forecasts. The probability that growth in the world's population will end during this century is 88%, somewhat higher than previously assessed. After mid-century, lower rates of population growth are likely to coincide with slower rates of ageing.

Abstract: Introduction Alzheimer's disease and related dementias (ADRD) cause a high burden of morbidity and mortality in the United States. Age, race, and ethnicity are important risk factors for ADRD. Methods We estimated the future US burden of ADRD by age, sex, and race and ethnicity by applying subgroup-specific prevalence among Medicare Fee-for-Service beneficiaries aged ≥65 years in 2014 to subgroup-specific population estimates for 2014 and population projection data from the United States Census Bureau for 2015 to 2060. Results The burden of ADRD in 2014 was an estimated 5.0 million adults aged ≥65 years or 1.6% of the population, and there are significant disparities in ADRD prevalence among population subgroups defined by race and ethnicity. ADRD burden will double to 3.3% by 2060 when 13.9 million Americans are projected to have the disease. Discussion These estimates can be used to guide planning and interventions related to caring for the ADRD population and supporting caregivers.

Abstract: 1. Introduction 1.1 Formalization 1.2 Elementary Characteristics of Populations 2. Life Tables 2.1 General Concepts 2.2 The Single Decrement Life Tables 2.3 The Abridged Life Table 2.4 The Multiple Decrement Life Table 2.5 Selected Properties of Model Life Tables 3. Reproduction 3.1 General Background 3.2 Per Capita Reproductive Rates 3.3 Reproductive Heterogeneity 3.4 Generalizations 4. Population I. Basic Concepts and Models 4.1 Background 4.2 The Stable Population Model 4.3 Population Projection 4.4 Fundamental Properties of Populations 5. Population II. Extensions of Stable Theory 5.1 Two-Sex Models 5.2 Stochastic Demography 5.3 Multiregional Demography 5.4 Demographic Theory of Social Insects: The Honeybee 5.5 The Unity of Demographic Population Models 6. Demographic Applications 6.1 Estimation 6.2 Curve Fitting 6.3 Mass Rearing: Basic Harvesting Concepts 6.4 Parasitoid Mass Rearing 6.5 Pros and Cons of Demographic Modeling

Abstract: If current trends continue the population of the United States will rise to 438 million in 2050 from 296 million in 2005 and 82% of the increase will be due to immigrants arriving from 2005 to 2050 and their U.S.-born descendants according to new projections developed by the Pew Research Center. Of the 117 million people added to the population during this period due to the effect of new immigration 67 million will be the immigrants themselves and 50 million will be their U.S.-born children or grandchildren. Among the other key population projections: Nearly one in five Americans (19%) will be an immigrant in 2050 compared with one in eight (12%) in 2005. By 2025 the immigrant or foreign-born share of the population will surpass the peak during the last great wave of immigration a century ago. The major role of immigration in national growth builds on the pattern of recent decades during which immigrants and their U.S.-born children and grandchildren accounted for most population increase. Immigrations importance increased as the average number of births to U.S.-born women dropped sharply before leveling off. (excerpt)