[Model of direction of the school system (demographic projection model)].
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Economics↗
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Results for “Demographic modelling”
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Predictive models of safety belt use: a regression analysis of MVOSS data.
A substantial portion of the U.S. population fails to regularly use their safety belts. The explanations for the differential belt use have addressed, for example, socioeconomics, state law, attitudes, and perceived likelihood of being ticketed. The current analyses create predictive models of safety belt use. Using NHTSA's Motor Vehicle Occupant Safety Surveys (Years 1998 and 2000; N = 9577), variables related to belt use were entered into backward stepwise logistic regressions to produce two predictive models (Demographic and Attitudinal) of safety belt use (Always versus Not always). The results indicated that belt use is a complicated issue as there were several interactions between variables. The Demographic predictive model contained main effects for, law types, socioeconomics, population density, a gender-law type interaction, and a three-way interaction between age, marital status, and vehicle type. The Attitudinal model included perceived effectiveness of the belt, fatalistic attitudes, and an interaction between perceived effectiveness of the belt and perceived risk of being ticketed. These models survived a multinomial logistic regression when belt use was parsed into three categories (Always, Part-time, and Infrequent). In addition to variables that affect belt use, the results suggested that the structure of "belt use" as a psychological/behavioral construct is more complicated than once thought. Specifically, a dichotomous breakdown of belt use (Always and Not always) oversimplifies the construct because the predictor factors sometimes affect "part-time" belt users differently than "infrequent" belt users (compared to "full-time" users). Many of the factors included in the models have been previously shown to impact belt use, but the interaction effects--indicating a more complicated relationship between these variables than previously suggested--may contribute to a better understanding of safety belt use.
Adolescent↗
Gene-history correlation and population structure.
Correlation of gene histories in the human genome determines the patterns of genetic variation (haplotype structure) and is crucial to understanding genetic factors in common diseases. We derive closed analytical expressions for the correlation of gene histories in established demographic models for genetic evolution and show how to extend the analysis to more realistic (but more complicated) models of demographic structure. We identify two contributions to the correlation of gene histories in divergent populations: linkage disequilibrium, and differences in the demographic history of individuals in the sample. These two factors contribute to correlations at different length scales: the former at small, and the latter at large scales. We show that recent mixing events in divergent populations limit the range of correlations and compare our findings to empirical results on the correlation of gene histories in the human genome.
Genetic Variation↗
The exponential multidimensional demographic projection model.
"This paper presents the multidimensional demographic projection on the basis of an exponential specification, which avoids the problems associated with the widely used specification on the basis of the linear integration hypothesis. It generalizes earlier work by Gill (1986) on Markov models for closed populations to include the case of open populations. A numerical illustration is also provided." (SUMMARY IN FRE)
Forecasting↗
Demographics in demographic-economic models: a note on the basic activity-commodity framework.
The authors present a critique of an early basic formulation for the development of demographic-economic models by M. Madden and P. W. J. Batey in 1980. They assert that more attention needs to be paid to the demographic components of these models and that "distinctions between household types must be treated more adequately, and mechanisms for changes in household type must be articulated and refined." A reply by M. Madden (pp. 1,537-42) is included, as well as a response by the authors (pp. 1,543-5).
Demography↗
Economic-demographic simulation models: a review of their usefulness for policy analysis.
"This paper assesses the usefulness of economic-demographic simulation models for policy analysis, emphasizing in particular the relevance of the current state of the art for agricultural development planners. A critical review of eight models defines the range of questions that can be answered with particular models, evaluating the reasonableness of their specifications and the probable quality of their performance. Suggestions concerning further research are also provided."
Agriculture↗
A dynamic multilevel model of demographic diversity and misfit effects.
In this study, the authors proposed and evaluated the linkages of a dynamic multilevel model of demographic diversity and misfit effects in a large sample of quick-service restaurants. Using a cross-level approach, the authors studied an employee's demographic misfit in relation to coworkers' demographics as a predictor of turnover risk over time. At the business-unit level, they studied changes in restaurant demographic diversity in relation to changes in profitability over time and unit turnover rates in relation to profitability. The authors also studied the impact of the match between the racial compositions of the restaurants and their communities on profitability. The results supported linkages between demographic misfit and turnover and partially supported a negative association between racial diversity and changes in profitability.
Adolescent↗
Count data models for demographic data.
"This paper deals with the estimation of single equation models in which the counts are regressed on a set of observed individual characteristics such as age, gender, or nationality.... We propose a generalized event count model to simultaneously allow for a wide class of count data models and account for over- and underdispersion. This model is successfully applied to German data on fertility, divorces and mobility." (SUMMARY IN FRE)
Demography↗
Risk-adjusted capitation based on the Diagnostic Cost Group Model: an empirical evaluation with health survey information.
OBJECTIVE: To evaluate the predictive accuracy of the Diagnostic Cost Group (DCG) model using health survey information. DATA SOURCES/STUDY SETTING: Longitudinal data collected for a sample of members of a Dutch sickness fund. In the Netherlands the sickness funds provide compulsory health insurance coverage for the 60 percent of the population in the lowest income brackets. STUDY DESIGN: A demographic model and DCG capitation models are estimated by means of ordinary least squares, with an individual's annual healthcare expenditures in 1994 as the dependent variable. For subgroups based on health survey information, costs predicted by the models are compared with actual costs. Using stepwise regression procedures a subset of relevant survey variables that could improve the predictive accuracy of the three-year DCG model was identified. Capitation models were extended with these variables. DATA COLLECTION/EXTRACTION METHODS: For the empirical analysis, panel data of sickness fund members were used that contained demographic information, annual healthcare expenditures, and diagnostic information from hospitalizations for each member. In 1993, a mailed health survey was conducted among a random sample of 15,000 persons in the panel data set, with a 70 percent response rate. PRINCIPAL FINDINGS: The predictive accuracy of the demographic model improves when it is extended with diagnostic information from prior hospitalizations (DCGs). A subset of survey variables further improves the predictive accuracy of the DCG capitation models. The predictable profits and losses based on survey information for the DCG models are smaller than for the demographic model. Most persons with predictable losses based on health survey information were not hospitalized in the preceding year. CONCLUSIONS: The use of diagnostic information from prior hospitalizations is a promising option for improving the demographic capitation payment formula. This study suggests that diagnostic information from outpatient utilization is complementary to DCGs in predicting future costs.
Adolescent↗
Technological change and the demographic transition model--India, a case study.
The concept of the demographic transition is re-examined in the context of India with particular reference to the demographic impact of technological change. In particular, the author examines whether "the demographic effects of a developing capitalist economy are due to (a) the extent of capitalist transformation of an economy; and (b) the nature and level of imported technological change."
Asia↗
Modeling the demographic effects of endocrine disruptors.
In this article we describe a series of strategic models of populations and individuals subject to challenge by endocrine disruptors. These models are not designed to be fitted to detailed data on specific species but rather are intended to provide general insights on the relative importance of different demographic mechanisms in the population context. Therefore, the models contain the minimum necessary biological detail, but in recompense they are highly accessible to mathematical analysis. We show that, over a range of models with contrasting biological detail, population viability is controlled by the number of female offspring that result from the average female's lifetime reproductive activity. Thus, male fertility changes have little effect at the population level until they become severe enough to reduce this average female output. We argue that in many circumstances endocrine disruptors are likely to produce directly deleterious effects on female fecundity at levels far below those required to reduce male fertility to dangerously low levels. Finally, we formulate a simple model of individual energetics that we argue can form the basis of a strategic discussion of the likely sensitivity of female demographic parameters to chemically induced changes in physiological function.
Animals↗
Persistence in population models with demographic fluctuations.
A persistence and extinction theory is developed through analytical studies of deterministic population models. Under hypotheses that require demographic parameters to fluctuate temporally, the populations may or may not oscillate. Extinction, when it occurs, is asymptotic. An hierarchy of persistence criteria, based upon fluctuations measured by time average means, is derived. In some situations a threshold value is found to separate persistent population models from those that tend to extinction. Application of the persistence-extinction theory is to the problem of assessing effects of a toxic substance on a population when toxicant inputs to the environment and to resources are oscillatory.
Demography↗
Non-homogeneous infinite sites model under demographic change: mathematical description and asymptotic behavior of pairwise distributions.
We developed a mathematical model, which makes possible to predict joint distributions of numbers of mismatches in two or more linked regions of the genome, based on the Infinite Sites Models, under mutation-drift equilibrium as well as under various patterns of population growth. With mutation rates varying in the region, one of the predictions is different correlation between numbers of mismatches in the two regions, depending on the pattern of the past population growth (constant, slowly growing, or rapidly growing). Also, for slower growth patterns of population sizes, the coalescence tree is not necessarily 'starlike'. Thus, the joint distribution of mismatches, predicted by the model, provides additional insights into the demographic history of the populations. We also developed expectations and variances of sample statistics under different growth scenarios. As an application we used a sample of mitochondrial sequences from hypervariable regions 1 and 2 (HV1 and HV2), representing major world populations (Europeans, Asians and Africans). The patterns of joint distributions of numbers of mismatches differ markedly from one population to another. In addition, there is a considerable variability in the proportion of numbers of mismatches between HV1 and HV2 sequences. The patterns of bivariate distributions from the HV1 and HV2 data in these data are consistent with those generated by the model involving a stepwise change in population size.
Asian People↗
Comparative population dynamics of mosquito-borne flaviviruses.
Among the members of the genus Flavivirus are several important human pathogens, including the dengue (DEN) and Japanese encephalitis (JE) viruses. From the analysis of gene sequence data of samples of these virus populations it is possible to infer phylogenetic relationships, which in turn can yield important epidemiological information, including their demographic history in humans. In this study, we use a recently developed method, based on coalescent theory, to infer the population dynamics of a variety of mosquito-borne flaviviruses. Our study involves the testing of alternative hypotheses, the estimation of confidence intervals around demographic model parameter values, and the placing of the maximum likelihood (ML) demographic model into a "real time" epidemiological history. We reveal that all the Flavivirus populations studied are growing at an exponential rate, with the rates of population growth of dengue virus serotypes 2 and 3 increasing rapidly in the recent past, and that of Japanese encephalitis virus changing from constant population size to exponential growth within the last century. We therefore demonstrate that the use of these coalescent methods may be extremely valuable in monitoring responses to interventions such as vaccination or vector control.
Arboviruses↗
[A model of demographic transformation in graph presentation].
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Demography↗
Next-generation phylogeography reveals unanticipated population history and climate and human impacts on the endangered floodplain bitterling (Acheilognathus longipinnis).
BACKGROUND: Floodplains harbor highly biodiverse ecosystems, which have been strongly affected by both past climate change and by recent human activities, resulting in a high prevalence of many endangered species in these habitats. Understanding the history of floodplain species over a wide range of timescales can contribute to effective conservation planning. We reconstructed the population formation history of the Itasenpara bitterling Acheilognathus longipinnis, an endangered floodplain fish species in Japan, over a broad timescale based on phylogenetic analysis, demographic modeling, and historical demographic analysis using mitogenome and whole-genome sequences. A genome sequence was newly assembled as a reference for the resequencing analysis. This bitterling is distributed in three plains separated by high mountain ranges and exhibits ecological characteristics well adapted to floodplain environments. RESULTS: Our analyses revealed an unexpected population branching pattern, gene flow, and timing of the differentiation that occurred within a few hundred thousand years, i.e., long after the mountain uplift that was assumed to be the primary geological cause of the population differentiation. The analyses also showed that all local populations experienced a severe decline during the last glacial and post-glacial periods. CONCLUSIONS: Our results suggest that the floodplain bitterling was able to disperse through unknown routes after mountain uplift and that its populations were strongly influenced by climatic and geographic changes in glacial-interglacial cycles and subsequent human activities, probably related to its floodplain-dependent ecology. The genomic data highlight the unanticipated distribution process of this species and the magnitude of the impact of human activities, with important implications for its conservation.
Endangered Species↗
Anthropological cybernetic model of demographic structures in the Republic of Croatia.
Intentions of the present investigation were: a) to apply a cybernetic model in description of demography of the Republic of Croatia and b) to underline specificity of this type model application in anthrolpology based on definitions of systems theory as a reaction against reductionism. The cybernetic model is based on the idea that continuous processes of childbirth and ageing can be represented by compartment analysis. Compartment subpopulations were subjected to: a) the elimination by mortality and emigration described by constants Fi,0, and b) the enlargement by the immigration process described by constants F0,i. The consistency of the model is evaluated through the comparison between model data and census. The model prediction of the census and mortality for the period between 1953 to 1998 is fair enough (within +/- 2%). Application of this type of models provides a possibility that the anthropological fitness of regions could be quantified. The obtained data reveals that autoreproduction of the system and its fitness could be described by the chaos theory.
Adolescent↗
[Territorial differences in migration: measurement and conclusions for plotting models of demographic forecasts].
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Demography↗