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Results for “Demographic modelling”

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At least 91 records · Page 5Linked to original sources
PubMed1990

[A demographic forecasting model with reference to population groups that intermarry, using the example of the Evangelical Church in Austria].

"This research note develops a multi-state population projection model in which inter-marriage between the states and the following uncertainty about the state of the children plays a major role. Since only 5% of the Austrian population belong to the Evangelical Church, but more than 80% of their members marry partners not belonging to the church, the question of the percentage of children from mixed marriages that become church members turns out to be vital for the future size and age composition of the church." Five different scenarios to the year 2030 are examined. (SUMMARY IN ENG)

Acculturation↗
PubMed2000

Antigenic drift of viruses within a host: a finite site model with demographic stochasticity.

We theoretically study the antigenic drift of viruses within an infected host, as observed in human immunodeficiency virus (HIV) and equine infectious anemia virus (EIAV) infections, assuming that a finite number of antigen-determining sites at the viral envelop gene are responsible for the specific immune response. The pattern of antigen evolution becomes more complex than that predicted from the previous one-dimensional antigen space models. If the viral growth rate is sufficiently large, the demographic stochasticity for the fate of a new antigen mutant can be neglected. The high dimensionality in the way a virus escapes the immune defense in genotype space could then causes a rapid increase in the antigenic diversity and the total viral density, until finally the whole antigen genotypes are used up. The viral population is then driven to extinction in a host by the enhanced immune response to all genotypes. In contrast, if the viral growth rate is moderate or small so that only a small fraction of new antigen mutants can survive during the initial endangered period of random extinction, the viral antigenic diversity and the total density remain bounded, thereby enabling them to persist for a prolonged period by shifting the dominant antigen types. The phylogenetic pattern of antigen divergence is well characterized by the mean number of surviving antigen mutants from an antigen genotype. The substitution rate at antigen-determining sites increases as the efficiency of host immune response increases.

Animals↗
PubMed1988

[[On the parameter estimation problems in the multiregional demographic growth model]].

"In this paper, we critically prove the formulas of Ledent-Rogers-Willekens.... Our procedure does not depend on multi-regional life table technique but on direct discretization of the continuous-time model. Here our main purpose is not to provide new results but to clear the conditions under which these methods for estimating the parameters can be applied. Finally, we give another method of calculation of parameters, which makes it possible to do a consistent disaggregated projection when we have already had an aggregated population projection." (SUMMARY IN ENG)

Demography↗
PubMed2000

When did the human population size start increasing?

We analyze the frequency spectra of all available human nuclear sequence data sets by using a model of constant population size followed by exponential growth. Parameters of growth (more extreme than or) comparable to what has been suggested from mtDNA data can be rejected for 6 out of the 10 largest data sets. When the data are separated into African and non-African samples, a constant size no-growth model can be rejected for 4 out of 8 non-African samples. Long-term growth (i.e., starting 50-100 kya) can be rejected for 2 out of 8 African samples and 5 out of 8 non-African ones. Under more complex demographic models, including a bottleneck or population subdivision, more of the data are compatible with long-term growth. One problem with the data used here is that a subset of loci may reflect the action of natural selection as well as of demography. It remains possible that the correct demographic model is one of constant population size followed by long-term growth but that at several loci the demographic signature has been obscured by balancing or diversifying selection. However, it is not clear that the data at these loci are consistent with a simple model of balancing selection; more complicated selective alternatives cannot be tested unless they are made explicit. An alternative explanation is that population size growth is more recent (e.g., upper Paleolithic) and that some of the loci have experienced recent directional selection. Given the available data, the latter hypothesis seems more likely.

Africa↗
PubMed1993

Sensitivity analysis in a multidimensional demographic projection model with a two-sex algorithm.

"Formulas are derived for the effect that a slight change in the occurrence/exposure rate of the multidimensional projection model has on the elements of the population vector. The projection model classifies the population by sex, age, and marital status. The model includes a two-sex algorithm in order to ensure consistency between numbers of male and female marriages, number of divorces for the two sexes, and new widows (widowers) and deceased spouses. The sensitivity functions and elasticities are applied to data from the Netherlands for the period 1980-1984. The results indicate that marriage market mechanisms, in particular competition and substitution effects, are reasonably well modelled."

Age Distribution↗
PubMed2000

Consistency and fluctuation theorems for discrete time structured population models having demographic stochasticity.

In this paper we prove a consistency theorem (law of large numbers) and a fluctuation theorem (central limit theorem) for structured population processes. The basic assumptions for these theorems are that the individuals have no statistically distinguishing features beyond their class and that the interaction between any two individuals is not too high. We apply these results to density dependent models of Leslie type and to a model for flour beetle dynamics.

Animals↗
PubMed1997

Student teacher anxieties related to class management, pedagogy, evaluation, and staff relations.

BACKGROUND: Anxiety is an important consideration in teaching, with implications for classroom success. AIMS: We investigated the nature of anxiety in student teachers. SAMPLES: Approximately 1000 student teachers in Canada were involved in four studies to explore education-related anxieties. METHODS: Incorporating a cross-cultural focus, student teachers were tested on an anxiety measure designed for British student teachers, then examined for (1) the impact of practice teaching, (2) the value of instructional preparation, (3) demographic variables, and (4) models that predict anxiety. RESULTS: Anxiety factors (i.e., evaluation, pedagogical, class management, and staff relations), similar to those for British participants, emerged with evaluation anxiety being highest. A practice teaching experience generated reduced anxiety for both sexes, but more so for females, with the greatest reductions for evaluation and pedagogical anxiety. In one study, participants reported anxieties prior to instruction (PRETEST), following instruction (POST-INSTR) and following practice teaching (POST-TEACH). Females showed higher anxiety ratings than males (PRETEST and POST-INSTR) but were comparable to males after practice teaching. Females in the lower grades division showed higher anxiety scores. Anxiety decreased between PRE-TEST and POST-INSTR for all four scales, and between POST-INSTR and POST-TEACH for evaluation, pedagogy and staff relations; however, class management anxiety did not decrease after practice teaching. Also, anxiety increased as placement grade level decreased. All models (demographic, experiential, and dispositional) were predictive but the best predictor was the psychological disposition to feel overwhelmed. CONCLUSIONS: Student-teacher anxieties are related to demographic variables, experiential variables, and dispositional variables.

Adult↗
PubMedDate not supplied

An evolutionary ecological perspective on demographic transitions: modeling multiple currencies.

Life history theory postulates tradeoffs of current versus future reproduction; today women face evolutionarily novel versions of these tradeoffs. Optimal age at first birth is the result of tradeoffs in fertility and mortality; ceteris paribus, early reproduction is advantageous. Yet modern women in developed nations experience relatively late first births; they appear to be trading off socioeconomic status and the paths to raised SES, education and work, against early fertility. Here, [1] using delineating parameter values drawn from data in the literature, we model these tradeoffs to determine how much socioeconomic advantage will compensate for delayed first births and lower lifetime fertility; and [2] we examine the effects of work and education on women's lifetime and age-specific fertility using data from seven cohorts in the Panel Study of Income Dynamics (PSID).

Adolescent↗
PubMed1988

Hypothetical vaccination of the Dutch population with a herpes simplex virus vaccine: estimation of the profitability using a demographic projection model.

The apparently increasing evidence of herpes simplex virus infections of the genital tract has focused attention on preventing the infection by vaccination. Herpes genitalis is not, however, the most quantitatively important clinical manifestation of herpes simplex virus infections. Because 41% of the hospitalized patients are younger than 20 years, vaccination of birth cohorts would be more favourable. In this paper the financial benefits of a hypothetical herpes simplex virus vaccination were calculated with the use of a population projection model. For the Netherlands, if the price of the hypothetical herpes simplex virus vaccine equals the cost price of the mumps component of the combined mumps-measles-rubella vaccine, the herpes vaccine would be profitable within 8 years.

Adolescent↗