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At least 253 records · Page 14Linked to original sources
PubMed1992

An evaluation of population forecast errors for Florida and its counties.

The authors evaluate the forecasting accuracy of population projections formulated at state and county levels for Florida. They find that "projections of Florida population made in the 1970s and 1980s had errors...of approximately 2-3 percent for 5-year horizons, 5-6 percent for 10-year horizons and 8-9 percent for 15-year horizons. County projections had errors averaging approximately 5, 10 and 15 percent for these three lengths of horizon, respectively. Based on comparisons with other studies of state and substate population projections, we believe this is a good record of forecast accuracy...."

Americas↗
PubMed1997

Bayesian demography: projecting the Iraqi Kurdish population, 1977-1990.

"Projecting populations that have sparse or unreliable data, such as those of many developing countries, presents a challenge to demographers. The assumptions that they make to project data-poor populations frequently fall into the realm of ¿educated guesses', and the resulting projections, often regarded as forecasts, are valid only to the extent that the assumptions on which they are based reasonably represent the past or future, as the case may be. These traditional projection techniques do not incorporate a demographer's assessment of uncertainty in the assumptions. Addressing the challenges of forecasting a data-poor population, we project the Iraqi Kurdish population using a Bayesian approach. This approach incorporates a demographer's uncertainty about past and future characteristics of the population in the form of elicited prior distributions."

Asia↗
PubMed1997

Doubling of world population unlikely.

Most national and international agencies producing population projections avoid addressing explicitly the issue of uncertainty. Typically, they provide either a single projection or a set of low, medium and high variants, and only very rarely do they give these projections a probabilistic interpretation. Probabilistic population projections have been developed for specific industrialized countries, mostly the United States, and are based largely on time-series analysis. On a global level, time-series analysis is not applicable because there is a lack of appropriate data, and for conceptual reasons such as the structural discontinuity caused by the demographic transition. Here we report on a new probabilistic approach that makes use of expert opinion on trends in fertility, mortality and migration, and on the 90 per cent uncertainty range of those trends in different parts of the world. We have used simulation techniques to derive probability distributions of population sizes and age structures for 13 regions of the world up to the year 2100. Among other things, we find that there is a probability of two-thirds that the world's population will not double in the twenty-first century.

Age Distribution↗
PubMed1988

Aging in China: demographic alternatives.

"In this article, China's future prospects have been discussed with regard to the aging of its population, by drawing heavily upon a new set of population projections prepared on the basis of the 1982 Population Census data. Unlike a variety of population projections for China currently available, our projections have placed heavy emphasis on the impact of improved mortality on China's aging process, by incorporating three alternative mortality assumptions. In our projections, all the alternative cases point to the acceleration of China's population aging, particularly after the year 2000.... From a policy point of view, these age compositional shifts will call for a change of priorities and a reallocation of resources to accommodate the rapidly growing proportion of elderly people and the steady decrease of young people in the population."

Age Distribution↗
PubMedDate not supplied

[A method for projecting the population according to size of locality. (Application to the case of Mexico's urban population in 1990)].

"In this article, a restricted components method is presented (because sex and age are not taken into account) to project the population classified according to the size of the locality.... The application is presented for urban centers (15,000 or more inhabitants) of Mexico in 1990, utilizing the trend in demographic growth for the 1960-1980 period." Data are from Mexican censuses conducted in 1960, 1970, and 1980. (SUMMARY IN ENG)

Americas↗
PubMed1985

Callosal and prefrontal associational projecting cell populations in area 7A of the macaque monkey: a study using retrogradely transported fluorescent dyes.

The spatial interrelationship of neurons in area 7a in the inferior parietal lobule that project through the corpus callosum to the corresponding field in the contralateral hemisphere or to the ipsilateral prefrontal cortex has been analyzed in macaque monkeys by using double-labeling procedures with retrogradely transported fluorescent dyes. The populations of callosal and associational projecting neurons have similar laminar distributions and are topographically intermingled. Less than 1% of the neurons were double-labeled, thus suggesting that the two populations are largely separate. Two-dimensional reconstructions of the distribution of labeled cells made on flattened reconstructions of the inferior parietal lobule revealed that the areal distribution of the two cortico-cortical output arrays is complex. Although each pattern of labeling showed some discontinuities in density, there was no obvious periodicity within or between the spatial distributions of the two projecting populations. It was consistently observed that the cortex of the lateral wall of the intraparietal sulcus, adjacent to area 7a, projects more heavily to the prefrontal cortex than does area 7a itself.

Animals↗
PubMed1992

Demographic prospects of Poland according to different projection assumptions.

The author examines population projections prepared in the 1980s for Poland. "The aim of the paper is to present and compare the assumptions of these projections and to discuss some of the resulting differences and similarities in [the] predicted demographic future of [the] population of Poland."

Developed Countries↗
PubMed1996

Population growth under changed fertility schedule in stability conditions.

"This paper aims to investigate some models for population projection under a gradual change in fertility schedule, and to evaluate integrals therein for their actual values.... Some formulae for population projection have been derived under stability conditions. The proposed formulae are also illustrated with some numerical values of the parameters involved therein. The merits and shortcomings are also discussed." (SUMMARY IN FRE)

Demography↗
PubMed1997

Modelling regional population growth in China.

"This paper develops a forward demographic rates-based multiregional population model on the basis of a set of multiregional population accounts. Forward emigration rates and immigration flows are adopted to describe the external migrations. The model is used to make consistent multiregional population projections of China at a provincial level.... Three sets of multiregional population projections of China at provincial level are made for the period 1987-2087. It is found that the national population trend is a combination of various regional population trends. Some regions, such as Zhejiang, will reach their population peak as early as the beginning of the next century while other regions, such as Xinjiang, will face continuous population growth in the first half of the next century."

Asia↗
PubMed1991

[Trends in the number of patients with senile dementia and need for nursing care in the upcoming 50 years--a demographic projection based on epidemiologic data for former West Germany].

According to population projections there will shortly be an increase in the number of aged people. Since these population groups show a high risk to develop old age dementia and because this sickness goes along with the need of care, it is necessary for planning future needs of buildings and funds to know about the extent of expected dementia and the number of people needing care. Based on population projections up to the year 2040 for the (West) German Länder of the Federal Republic of Germany and based on four epidemiological studies, we developed a model to project empirically the number of dementia cases for the next 50 years. This model is based on an exponential growth of prevalence with increasing age. According to our estimates the number of patients with severe and moderate dementia will rise by about 50% from 1990 until 2040. The expected number of people needing care is estimated to facilitate prospective planning as well as timely provision of adequate financial and personnel resources.

Aged↗
PubMed1986

Parameterized multistate population dynamics and projections.

"This article reports progress on the development of a population projection process that emphasizes model selection over demographic accounting. Transparent multiregional/multistate population projections that rely on parameterized model schedules are illustrated [using data primarily from a number of developed countries, particularly Sweden], together with simple techniques that extrapolate the recent trends exhibited by the parameters of such schedules." The author notes that "the parameterized schedules condense the amount of demographic information, expressing it in a language and variables that are more readily understood by the users of the projections. In addition, they permit a concise specification of the expected temporal patterns of variation among these variables, and they allow a disaggregated focus on demographic change that otherwise would not be feasible."

Demography↗
PubMed2002

Pattern of variation in avian population growth rates.

A central question in population ecology is to understand why population growth rates differ over time. Here, we describe how the long-term growth of populations is not only influenced by parameters affecting the expected dynamics, for example form of density dependence and specific population growth rate, but is also affected by environmental and demographic stochasticity. Using long-term studies of fluctuations of bird populations, we show an interaction between the stochastic and the deterministic components of the population dynamics: high specific growth rates at small densities r(1) are typically positively correlated with the environmental variance sigma(e)(2). Furthermore, theta, a single parameter describing the form of the density regulation in the theta-logistic density-regulation model, is negatively correlated with r(1). These patterns are in turn correlated with interspecific differences in life-history characteristics. Higher specific growth rates, larger stochastic effects on the population dynamics and stronger density regulation at small densities are found in species with large clutch sizes or high adult mortality rates than in long-lived species. Unfortunately, large uncertainties in parameter estimates, as well as strong stochastic effects on the population dynamics, will often make even short-term population projections unreliable. We illustrate that the concept of population prediction interval can be useful in evaluating the consequences of these uncertainties in the population projections for the choice of management actions.

Analysis of Variance↗