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PubMed2004

Some demographic issues affecting private health insurance.

There will be significant changes in the demography of persons with Private Health Insurance (PHI). Two methods of projecting PHI coverage are discussed in this paper. The first assumes the only factors affecting PHI coverage are demographic change and mortality and facilitates comparisons between actual and projected PHI coverage. The second projects the percentage of the population insured in each five year age cohort, and makes allowance for changes in PHI coverage due to all factors. Demographic change will increase Registered Health Benefit Organization (RHBO) premiums by 1.7% per annum. The role of these projections in analysing the effect of future premium increases on PHI retention rates is also discussed.

Actuarial Analysis↗
PubMed2005

Sex ratio bias, male aggression, and population collapse in lizards.

The adult sex ratio (ASR) is a key parameter of the demography of human and other animal populations, yet the causes of variation in ASR, how individuals respond to this variation, and how their response feeds back into population dynamics remain poorly understood. A prevalent hypothesis is that ASR is regulated by intrasexual competition, which would cause more mortality or emigration in the sex of increasing frequency. Our experimental manipulation of populations of the common lizard (Lacerta vivipara) shows the opposite effect. Male mortality and emigration are not higher under male-biased ASR. Rather, an excess of adult males begets aggression toward adult females, whose survival and fecundity drop, along with their emigration rate. The ensuing prediction that adult male skew should be amplified and total population size should decline is supported by long-term data. Numerical projections show that this amplifying effect causes a major risk of population extinction. In general, such an "evolutionary trap" toward extinction threatens populations in which there is a substantial mating cost for females, and environmental changes or management practices skew the ASR toward males.

Aggression↗
PubMed2006

Global genetic positioning: evidence for early human population centers in coastal habitats.

For an alternative perspective on relationships among human populations, we combined genetic and geographic information, using allele frequency gradients to place populations and individuals on the globe. Reanalyzing published data on 51 worldwide populations [Rosenberg, N. A., Pritchard, J. K., Weber, J. L., Cann, H. M., Kidd, K. K., Zhivitovsky, L. A. & Feldman, M. W. (2002) Science 298, 2381-2385] reveals five geographic clusters lying in plausible sites either of early agricultural innovation or on ancient migration routes. Also, the inferred sites show significant association with coastlines, suggesting that most early humans lived near large bodies of water. Our approach is flexible, and developments should prove useful both for exploring historical demography and for the identification of likely origin for unknown forensic samples.

Africa South of the Sahara↗
PubMed1972

A study of optimum population levels--a progress report.

The purpose of this study is to explore different approaches and to develop a methodology that will allow a calculation of "optimum levels of population." The discussion is specialized to the United States, but the methodology should be broad enough to handle other countries, including less-developed countries. The study is based on economics, but with major inputs from the areas of technology, natural resources management, environmental effects, and demography. The general approach will be to develop an index for quality of life (IQL or Q-index) and to maximize this index as a function of level and distribution of population. The technique consists of a reshuffling of national income accounts so as to be able to go from the Gross National Product (GNP) to the index for quality of life, plus a careful discussion of what is and what is not to be included. The initial part of the study consists of a projection of the index for quality of life as population level increases and as population distribution changes, under the assumption of various technologies, particularly as these relate to the consumption of minerals, energy, and other natural resources. One would expect that as economic growth continues, an increasing fraction of expenditures would be for the diseconomics produced by population growth and economic growth. This study should be useful by providing a rational base for governmental policies regarding population, both in the United States and abroad. Another application of the study is to technology assessment, by measurement of the impact on economic well-being through the introduction of new technologies. Therefore, one can gauge the necessary and desirable investments in certain new technologies. In general, mathematical models resulting from this study can become useful diagnostic tools to analyze the consequences of various public and private policy decisions.

Demography↗
PubMed1990

Delayed reproduction and fitness in variable environments.

Many organisms delay the initiation of reproduction even though such delay is not adaptive in a constant environment. Theoretical arguments in this paper show that delaying reproduction can increase fitness in a sufficiently variable environment. This paper uses stochastic demography to analyze the fluctuating population structure produced by environmental uncertainty. The results explain previously puzzling features of life cycle delays observed in nature, predicting that populations of the same species living in environments of differing harshness can display different life history phenotypes, a number of distinct life history phenotypes can coexist neutrally within a single population, and genetic polymorphisms are easily maintained if heterozygotes have intermediate life history phenotypes.

Adaptation, Physiological↗
PubMed1999

Allelic association between marker loci.

Allelic association has proven useful to refine the location of major genes prior to positional cloning, but it is of uncertain value for genome scans in complex inheritance. We have extended kinship theory to give information content for linkage and allelic association. Application to pairs of closely linked markers as a surrogate for marker x oligogene pairs indicates that association is largely determined by regional founders, with little effect of subsequent demography. Sub-Saharan Africa has the least allelic association, consistent with settlement of other regions by small numbers of founders. Recent speculation about substantial advantages of isolates over large populations, of constant size over expansion, and of F1 hybrids over incrosses is not supported by theory or data. On the contrary, fewer affected cases, less opportunity for replication, and more stochastic variation tend to make isolates less informative for allelic association, as they are for linkage.

Africa South of the Sahara↗
PubMed2006

Nutritional status of Amerindian children from the Beni River (lowland Bolivia) as related to environmental, maternal and dietary factors.

OBJECTIVES: To report the nutritional status of children aged up to 15 years and their mothers living in a remote Amazonian area of Bolivia, and to study its main social, familial and maternal determinants. SETTING: Fifteen Beni River communities located at the foot of the Andes. DESIGN: Cross-sectional survey of riverside populations. All childbearing mothers and their children in the 15 communities were examined. METHODS: Information on household production, dietary habits and demography was collected. Individual clinical, anthropometric and parasitological examinations were carried out. SUBJECTS: A total of 631 persons were examined: 171 mothers and 460 children and adolescents aged 0 to 15 years. RESULTS: There were no cases of severe wasting, but 41% of 0-5-year-olds and 36% of 5-10-year-olds were stunted. Among 346 stool specimens examined, 75% were positive for at least one helminth. Diversity of food and quality of diet were satisfactory in 54% of households, but 27% had low diversity scores. Mothers were lighter and shorter than those observed at the national level: 20% had height below 145 cm. Prevalence of anaemia (42%) was also higher. In pre-school children, multivariate analysis indicated a relationship between growth retardation and household factors such as dietary quality, ethnic group and clinical state, but not maternal anthropometry. In contrast, in school-age children and adolescents, growth retardation was related to maternal characteristics. CONCLUSIONS: Growth retardation appeared mainly during the weaning period and did not seem to improve thereafter. To ameliorate this situation, an effort should be made to prevent common parasitic and infectious diseases in young children. Follow-up of pregnant mothers during pregnancy and delivery also needs to be reinforced.

Adolescent↗
PubMed1996

The development and use of demographic models.

In this review, we first examine two classical demographic models - conventional life tables and stable populations - and a modern generalization of stable population theory; we then discuss mathematical models of conception and birth. These models involve purely mathematical relations in formal demography as opposed to empirical regularities. Next we consider model age schedules of mortality, nuptialitiy, marital fertility, fertility, and migration that are explicitly based on such empirical patterns. We close this empirical section with a discussion of model stable populations, which are based on model life tables. We next examine the use of demographic models in forecasting future mortality, nuptiality, and fertility and in population projection. Following a discussion of microsimulation models, which gives us the opportunity to mention model age schedules of post partum amenorrhoea and of sterility, we close with observations about the purposes and uses of demographic models.

Demography↗
PubMed1988

Economic development, population and primacy.

"This paper investigates the relationship between economic development and primacy advanced by El-Shakhs, Mera and others, and finds no statistically significant link when obvious demographic influences are taken into account. Three variables (national population, the urban population share, and a Latin American dummy) explain 40% of the variation in primacy in a sample of 116 countries (including 82 developing countries). Economic factors do not appear to be important. Demography may be more influential than economics in attempts to explain primacy."

Demography↗
PubMed1994

Socio-demographic trends in Northern Ireland, 1971 to 1991.

"Northern Ireland has demographic and socio-economic structures which set it apart from the rest of the United Kingdom and religion impacts on this social demography more than in any other 'developed' society. Peripherality also serves to underpin some of the distinctiveness of the Province. Socio-economic and demographic data from Population Censuses and demographic data from Annual Reports of the Registrar General are analysed. The socio-demographic trends between 1971, 1981 and 1991 are traced and the spatial patterns are described. Many of the spatial patterns have been remarkably persistent over time and the problems that arise from this are unlikely to be addressed fully given the Province's perverse polity."

Demography↗
PubMed1984

Iron and infection in infancy--report on field studies in Papua New Guinea: 1. Demographic description and pilot surveys.

Madang district was selected for a longitudinal study of the effects of iron prophylaxis on infectious morbidity in infancy and the topography, climate, domicile, ethnology, demography, disease patterns, nutrition and health services of the district are described. The area has a tropical, humid climate and a mixed economy. Pneumonia was the main killing disease at all ages, and malaria was endemic. A base hospital and well organized maternal and child health services ensured that morbidity surveillance would be optimal. Pilot haematological surveys confirmed a high incidence of anaemia in infancy. Mean haemoglobin between nine and 52 weeks of age was 8.6 g/dl. Results suggested that malaria and iron deficiency were important causes of this anaemia.

Age Factors↗
PubMed1989

Leslie matrix models.

A review of the Leslie matrix model theory and its literature 1941-1987 is presented. The point of view is that of a mathematician who focuses on the parts of the theory which are relevant to demography. Works of a decidedly applied nature are not dealt with.

Age Factors↗
PubMed1992

Multistate life-tables and regression models.

"A survey is given of the use of modern statistical techniques in event history analysis, and in particular in the study of multi-state life-tables in demography. Emphasis is placed on the interplay between partial likelihood and nonparametric maximum likelihood based methods, a) when analysing semi-Markov models or models with repeated spells, and b) in frailty models for unobservable heterogeneity."

Demography↗
PubMedDate not supplied

Community-based rehabilitation in the Lao People's Democratic Republic.

An overview of the demography of the Lao People's Democratic Republic along with estimates of disability prevalence are given. The legislative response of the central government to disability and handicap is also described. The implementation, organization and manpower of the community-based rehabilitation (CBR) programme is discussed and illustrated using a case study from the Luang Prabang Province.

Community Health Services↗
PubMed2001

A measure of the intensity of response to alcohol in a military population.

Heavy drinking and associated problems are relatively common in young men, including those in a military setting. This article explores characteristics of alcohol intake and associated difficulties and their relationship to a self-report of the usual intensity of response to alcohol in a sample of U.S. Marines. Two questionnaires related to demography and alcohol use histories, along with a simple, 12-item self-report measure of the usual number of drinks to experience an effect (the Self-Rating of the Effects of Alcohol, SRE) were administered to 1320 U.S. Marines. The sample had an average age of 22 years, 78% were Caucasian, and 92% were enlisted personnel. The relationships and correlations among drinking characteristics and problems and the usual number of drinks for an effect were determined. These subjects drank an average of 6 days per month, consuming an average of almost six drinks per drinking day, and reported more than three times per month in which they consumed six or more drinks per occasion. Consistent with studies of other populations, the SRE measures of intensity of response to alcohol showed a positive correlation with both drinking practices and problems, with the latter remaining significant even after controlling for recent drinking practices. The prodigious level of alcohol intake and associated problems, along with the SRE scores, indicate that the Marine Corps personnel are at especially high risk for alcohol-related life problems. These data also support the potential usefulness of the SRE both in identifying individuals likely to have more severe alcohol profiles and in educating individuals regarding their levels of risk for alcohol abuse and dependence.

Adult↗
PubMed2004

Measles metapopulation dynamics: a gravity model for epidemiological coupling and dynamics.

Infectious diseases provide a particularly clear illustration of the spatiotemporal underpinnings of consumer-resource dynamics. The paradigm is provided by extremely contagious, acute, immunizing childhood infections. Partially synchronized, unstable oscillations are punctuated by local extinctions. This, in turn, can result in spatial differentiation in the timing of epidemics and, depending on the nature of spatial contagion, may result in traveling waves. Measles epidemics are one of a few systems documented well enough to reveal all of these properties and how they are affected by spatiotemporal variations in population structure and demography. On the basis of a gravity coupling model and a time series susceptible-infected-recovered (TSIR) model for local dynamics, we propose a metapopulation model for regional measles dynamics. The model can capture all the major spatiotemporal properties in prevaccination epidemics of measles in England and Wales.

Demography↗
PubMed2005

Prior information in behavioral capture-recapture methods: demographic influences on drug injectors' propensity to be listed in data sources and their drug-related mortality.

The authors present findings from a Bayesian analysis of Scotland's four primary capture-recapture data sources for 2000 that was carried out to estimate numbers of current injecting drug users by region (Greater Glasgow vs. elsewhere in Scotland), sex (male vs. female), and age group (15-34 years vs. > or =35 years). A secondary goal of the analysis was to obtain Bayesian estimates and credible intervals for the demographic influences on Scotland's drug-related death rate per 100 current injectors. Incorporation of informative priors altered the models with highest posterior probability. Expert opinion on how demography influenced Scottish drug injectors' propensity to be listed in different data sources was taken into account, along with external information about European injectors' drug-related death rates and male:female ratios. Higher drug-related mortality was confirmed in older drug injectors and those outside of Greater Glasgow. Female injectors' lower drug-related death rate was not sustained beyond 34 years of age. The authors recommend that demographic influences be accommodated in behavioral capture-recapture estimation, especially when it is a prelude to secondary analysis, such as the analysis of drug-related death rates presented here.

Adolescent↗
PubMed1986

Denominator definition by the utilization correction factor method.

Most clinical research in the United States has been carried out in atypical populations. This study, done in a network of primary care populations in Virginia, calculates the denominator by the utilization correction factor method and compares the demography with that of the population of the state. The demographic characteristics of the patients in the network are very similar to those of the underlying populations and on the same order of state-of-the-art sampling methods in current use.

Adolescent↗