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Results for “Population Projection”

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At least 217 records · Page 12Linked to original sources
PubMed2005

Projected population-level effects of thiobencarb exposure on the mysid, Americamysis bahia, and extinction probability in a concentration-decay exposure system.

Population-level effects of the mysid, Americamysis bahia, exposed to varying thiobencarb concentrations were estimated using stage-structured matrix models. A deterministic density-independent matrix model estimated the decrease in population growth rate (lambda) with increasing thiobencarb concentration. An elasticity analysis determined that survival of middle stages provided the largest contribution to lambda. Decomposing the effects of lambda in terms of changes in the matrix components determined that reduced reproduction had a large influence on population dynamics at lower thiobencarb concentrations, whereas reduced survivorship had the largest impact on populations at higher concentrations. A simulation model of a concentration-decay system was developed to demonstrate the importance of integrating chemical half-life and management practices in determining population viability. In this model, mysids were originally exposed to a high thiobencarb concentration (300 microg/L) that decayed an order of magnitude in the number of mysid generations corresponding to thiobencarb half-life values under three different exposure regimes. Environmental stochasticity was added to the model to estimate the cumulative extinction probability of mysids exposed to fluctuating concentrations of thiobencarb in random environments. The cumulative extinction probability increased with thiobencarb half-life, stochasticity, and concentration present at the time of a new exposure. The model demonstrated the expansion of population projection models in determining the ecological impact of a population exposed to pesticides.

Animals↗
PubMed2006

Demographic characteristics of endodontic practice sites in the United States.

Few studies have addressed the demographic characteristics of dental practice sites including endodontic practice sites. This study investigated the demographic characteristics of endodontic practice sites in the United States. Demographic data and endodontic practices were organized by zip codes and analyzed using discriminant analysis. The demographic characteristics associated with zip codes that contained an endodontic practice were determined versus the characteristics of zip codes that did not contain an endodontic practice. The resulting model correctly classified 93.7% of the 30,171 zip code areas based upon the presence or absence of an endodontic practice. The variables most closely associated with a zip code containing an endodontic practice included: number of dental practices (nonendodontic), population size, percent of adult population with a college degree, size of employed population, projected population growth (2005 to 2010), percent of population over 64 years old, and median housing value.

Adult↗
PubMed1993

Capitation funding: population, age, and mortality adjustments for regional and district health authorities in England.

OBJECTIVE: To assess the effect of each of the components of the national capitation funding formula--population projections and age and mortality weighting--at regional and district level. DESIGN: Application of age-cost and mortality weights to the projected 1997 populations of regions and districts, based on the Department of Health public health common dataset. SETTING: Regional and district health authorities in England. RESULTS: The application of the age-cost and mortality weights to projected populations resulted in greater changes in the shares of weighted populations relative to the estimated 1991 population at district level (mean 0, range -17% to 28%) than at regional level (mean 0, range -9% to 6%). At district level mortality weights had less scope for influence (mean 0, range -9% to 14%) than population projections (mean 0, range -16% to 31%) or age weights (mean 0, range -20% to 30%). CONCLUSIONS: The adjustments to the 1991 population shares due to the application of the national capitation funding formula depend on the interaction of three elements: the projected population by age group, the age-cost weight, and the mortality weight. Since each is open to uncertainty, either in terms of measurement (projected population, particularly for births and the over 85s) or method (derivation of the age-cost and mortality weights), the formula should be implemented cautiously at district level. Ways should be considered of incorporating elements of uncertainty into the model. Further research is required on the elements and degree of uncertainty in each of these components, as well as on the relative health needs of different populations.

Adolescent↗
PubMedDate not supplied

Projecting Igbo population to the year 2000 and beyond.

"This study addresses the issues and the consequences of the growth of [the] Igbo population [of Nigeria] from the pre-colonial period to the year 2000 and beyond; it reveals that though the political crises of the Nigerian Civil War have reduced the tempo of the growth of the population, the high fertility rate observed in Igbo society will over time lead to a rapid recovery in the growth of the population." (SUMMARY IN FRE AND ITA)

Africa↗
PubMed1986

Accounting for migration in cohort-component projections of state and local populations.

Migration is the most difficult component of state and local population growth to forecast accurately because it is more volatile than either births or deaths, and subject to much larger fluctuations within a short period of time. In addition, migration rates can be based on several different measures of migration and the base population. The choice of the appropriate base population has received little attention from demographic researchers, but can have a tremendous impact on population projections. In this article, I develop three different models for projecting migration, each using a different denominator for migration rates. Population projections for ten states are made, using identical data and cohort component techniques, except for the different formulations of migration rates. Differences among the three sets of projections are noted, and conclusions are drawn regarding their usefulness as forecasts of population growth.

Emigration and Immigration↗