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PubMed1992

Projecting the number of new AIDS cases in the United States.

"This paper reviews the two leading methods used to project the number of AIDS cases: back calculation and extrapolation. These methods are assessed in light of key features of the HIV/AIDS epidemic and of data on the epidemic; they are also assessed in terms of the quality of the projections they yield. Our analysis shows that both methods have tended to overproject, often by sizable amounts, the number of AIDS cases in the United States....A new method for projecting AIDS cases is proposed that exploits knowledge about the process generating AIDS cases and that incorporates readily available information about rates of new HIV infection.... Relative to the method of extrapolation, this method projects 22,000 fewer new AIDS cases for 1995 (a 36% difference). This method also projects that intravenous drug users will replace homosexual/bisexual men as the dominant transmission category for AIDS."

Acquired Immunodeficiency Syndrome↗
PubMed1992

The demographic impact of AIDS in sub-Saharan Africa: short- and long-term projections.

"This paper describes the methodology used to incorporate AIDS mortality in recently revised World Bank population projections.... The paper first reviews different approaches for projecting AIDS and its demographic consequences. This is followed by a summary of an epidemiological model that simulates the spread of HIV used in this analysis, and a demographic model that translates mortality from AIDS into population outcomes. These models are then used in a set of simulations, from which the effect of current HIV prevalence on projected future mortality is extracted. Finally, the extracted equations linking current HIV prevalence with future mortality indicators are applied to sub-Saharan countries with a measurable level of current HIV prevalence."

Acquired Immunodeficiency Syndrome↗
PubMed1992

Stochastic population forecasts and their uses.

"The properties and uses of stochastic forecasts are discussed here. For linear stochastic projections, we show how the computation of forecast moments and the statistical distribution of forecasts depend on the multiplicative and autoregressive structure of the dynamics. Both scalar and vector projection methods are discussed, and their similarities are explored. Next we discuss the uses of stochastic forecasts, arguing that it is important to relate forecasts to the specific decision-making criteria of particular forecast users. The example of [the U.S. system of] Social Security is used to show how a dynamic programming approach may be used to explore alternative decisions in a probabilistic context."

Americas↗
PubMed1992

Modeling and forecasting U.S. sex differentials in mortality.

"This paper examines differentials in observed and forecasted sex-specific life expectancies and longevity in the United States from 1900 to 2065. Mortality models are developed and used to generate long-run forecasts, with confidence intervals that extend recent work by Lee and Carter (1992). These results are compared for forecast accuracy with univariate naive forecasts of life expectancies and those prepared by the Actuary of the Social Security Administration."

Americas↗
PubMed1992

Projecting the future size and health status of the U.S. elderly population.

"A projection model based on a multivariate continuous state, stochastic process is presented. The model allows multiple time-varying covariates to be used so parameters can be estimated from time series information on health changes and mortality, and their interaction. Health changes are simulated by altering parameters controlling the age trajectory and diffusion of risk factor means, variances, and covariances....By increasing the information used in projections it may be possible to better (a) anticipate the state of health at extreme ages, (b) forecast changes in health at specific ages over time, (c) stimulate the effects of specific interventions, and (d) determine the sensitivity of outcomes to a range of interventions."

Adult↗
PubMed1992

Immigration and immigrant generations in population projections.

This paper proposes a new model for population projections. This model projects an initial population under conditions of fertility, mortality, and international migration (like standard cohort-component models), but considers the population arrayed by generation. The model incorporates 4 generations: a foreign-born first generation (the immigrants), a second generation (sons and daughters of immigrants), a third generation (grandsons and granddaughters of immigrants), and fourth-and-higher generations. The model requires fertility, mortality, and migration equations by generation, which take a somewhat different form than in conventional cohort-component population projection. Consideration of the model also makes apparent that assignment of births to generations may not follow a simple form: the paper presents a method for including the empirical description of intergenerational births within the generational framework. As an example, the authors examine the next century of population growth for the Asian, Black, Hispanic, and White non-Hispanic populations in the US, comparing their growth rates and their composition within the total US population. With annual net immigration of 950,000, the total US population of 249 million in 1990 will top 400 million in 2070 and reach about 432 million in 2090. Thus, the level of immigration and emigration assumed in these projections suggests considerable population growth for the next hundred years. The racial/ethnic composition of the US will shift markedly during the next century, as described in the paper.

Americas↗
PubMed1992

Evaluating the forecast accuracy and bias of alternative population projections for states.

"A common perception among producers (and users) of population projections is that complex and/or sophisticated techniques produce more accurate forecasts than simple and/or naive techniques. In this paper we test the validity of that perception by evaluating the forecast accuracy and bias of eight commonly used projection techniques drawn from...four categories [trend extrapolation, ratio extrapolation, cohort-component, and structural]. Using data for [U.S.] state population projections from a number of different time periods, we find no evidence that complex and/or sophisticated techniques produce more accurate or less biased forecasts than simple, naive techniques."

Americas↗
PubMed1992

A comparison of four methods for projecting households.

"The purpose of this paper is to extend the headship rate method for projecting households to encompass both sexes. Four models are considered that explicitly incorporate the impact of changes in the number of men and women on the number and joint age distribution of husband-wife households. The models are applied to the Philippines using data from the 1988 National Demographic Survey to project households to 2010. The models are also evaluated by 'backcasting' and comparing the results with special tabulations from the 1970 and 1980 censuses and the 1975 National Demographic Survey."

Age Distribution↗
PubMed1992

Into the twenty-first century with British households.

"This paper takes [U.K.] General Household Survey (GHS) data at the micro level and ages these households by simulation to the year 2001. Differing scenarios are considered in order to accommodate high and low variants of each household type in the British household distribution."

Age Factors↗
PubMed1986

Urban change in the third world: are recent trends a useful pointer to the urban future?

"This paper has three aims. The first is to examine the reliability of the data base for the statistics which are used as the basis for commenting on urban change in 'the Third World'. The second is to explore whether valid generalisations about urban change can be made for the Third World. And the third is to examine the validity of United Nations projections for the Third World's urban future."

Data Collection↗
PubMed1993

Rural-to-urban and urban-to-urban migration patterns in Colombia.

"The object of this study was to identify the factors that may explain, and help to predict, the direction and intensity of migration flows from rural to urban and from urban to urban areas in Colombia. For this purpose, statistical models were used with a view to obtaining a better insight into the push-and-pull causes of the migration patterns and a better understanding of their consequences."

Americas↗
PubMed1991

Growth and equity effects of changing demographic structures in the Netherlands: simulations within a social accounting matrix.

"This paper deals with the economic consequences of a changing demography in an industrialized country, namely the Netherlands. The analytical framework chosen is that of general equilibrium as statistically given by the social accounting matrix (SAM) in which we introduce households by size for the present economic demographic situation (1981) and for a future simulated situation (2010) featuring in particular a relative increase in one-person households (individualization). The income (output) multipliers of both SAMs show a positive growth bias towards three and more person households and towards mining, public utilities, trade and banking."

Demography↗
PubMed1983

Monitoring mortality: a state-space approach.

"A state-space model is developed which provides estimates of decrements in a dynamic environment. The model integrates the actual unfolding experience and a priori or Bayesian views of the rates. The estimates of present rates and predicted future rates are continually updated and associated standard errors have simple expressions. The model is described and applied in the context of mortality estimation but it should prove useful in other actuarial applications. The approach is particularly suitable for dynamic environments where data are scarce and updated parameter estimates are required on a regular basis. To illustrate the method it is used to monitor the unfolding mortality experience of the retired lives under an actual pension plan."

Adult↗
PubMed1996

Age cohort analysis of the 20th century decline in U.S. farm numbers.

"The demographic component of the decline in U.S. farm numbers is analysed by tracking the size of farm operator age cohorts.... Cohort profiles indicate an inverted U-shape in the relationship between farm numbers and cohort age. Successive cohorts have been smaller than their predecessors, and withdrawal rates of older operators have fallen in recent years. Projections based on entry-withdrawal patterns for 1987-1992 suggest decline in farm numbers from 1.93 million in 1992 to 1.48 million in 2002 and 1.29 million in 2007. Imbalance between withdrawing older operators and younger new entrants could encourage a broadening of the pool of farm entrants and changes in farm ownership, operating and financing arrangements."

Age Factors↗
PubMed1992

An estimate of the future size of the tuberculosis problem in sub-Saharan Africa resulting from HIV infection.

The impact of the human immunodeficiency virus (HIV) on tuberculosis is well documented. Its effect in populations with a high proportion of dually infected individuals is likely to be significant. Sub-Saharan Africa is one such region and to better document the effect of HIV infection on tuberculosis there we developed a mathematical model to predict the likely extra numbers of tuberculosis cases due to it. A mathematical model was developed using a variety of scenarios giving a range of risks for the period 1980-2000. The four scenarios included (1) a low rate of 1% risk of tuberculosis infection in year 0 (1980) with 45% tuberculosis infection prevalence, and an HIV prevalence of 2% in 1989; (2) a 2% risk of tuberculosis infection in year 0 with 60% tuberculosis infection prevalence, and a 2% HIV prevalence in 1989; (3) a 2% risk of tuberculosis infection in year 0 with 60% tuberculosis infection prevalence, and a 10% HIV prevalence in 1989; and (4) a 2% risk of tuberculosis infection in year 0 with 60% tuberculosis infection prevalence and a 20% HIV prevalence in 1989. Under scenarios 1 and 2, a 50-60% increase in smear-positive rates in the subpopulation (15-45 years old) is predicted for the year 2000, under scenario 3, smear-positive rates in the subpopulation in the year 2000 are expected to increase four-fold from the 1980 baseline. Under scenario 4, a 10-fold increase in smear-positive rates in 2000 is expected in the subpopulation. Under this scenario, total disease will have increased 12-fold in the subpopulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗