Voodoo forecasting: Technical,political and ethical issues regarding the projection of local population growth

The case of an energy production community in Colorado is used to illustrate a) the great need for reliable subnational population forecasts, especially in communities expecting rapid population growth, and b) why such projections, as currently performed, cannot be reliable. Explanations for failure in forecasting are found in the methods themselves, the unavailability and unreliability of key data, politics, and the intrusion of the designers' and users' values into the forecasting models. As one solution it is proposed that forecasting be reconceptualized from a technical to an ethical issue and that it be based upon an active rather than a passive planning/forecasting philosophy. As such, the community and industry would set a desired, realistic goal, and forecasting models would be run backwards to determine the economic-demographic paths by which this goal could be achieved.     

Occupations,migration, sex ratios,and nuptiality in nineteenth century English communities: A model of relationships

Two effects of occupational structure on nuptiality levels are examined: a direct functional effect related to the influence of socioeconomic characteristics on the feasibility and desirability of marriage, and an indirect structural effect related to nuptiality levels via sex selective migration patterns and population sex ratios. Our analysis shows that nuptiality levels in nineteenth century English and Welsh districts were responsive to occupational variation and that both direct and indirect effects were significant. Our results suggest that socioeconomic factors, often overlooked in favor of cultural explanation, must be considered in the analysis of nuptiality.     

Starting,stopping, and spacing during the early stages of fertility transition: The experience of German village populations in the 18th and 19th centuries

Examination of the reproductive histories of a sample of German married couples during the 18th and 19th centuries provides insights into behavioral changes involved in the shift from natural fertility to deliberate marital fertility control. A simple accounting scheme is used to assess the relative contributions of starting, spacing, and stopping to changes in family size during the initial phases of the fertility transition. The results suggest that in rural Germany, attempts to terminate childbearing prior to the end of the reproductive span were far more important in initiating the onset of fertility transition than efforts to deliberately prolong intervals between births or changes in the timing of the start of childbearing.     

Trade, population growth, and the environment in developing countries

We examine pollution in a developing country where fertility is endogenous and wealth increases welfare through status. When the country has defective environmental laws, it has a comparative advantage in capital-intensive “dirty” goods. Gains from trade due to trade liberalization then increase income and boost population growth. With strong incentives to save, they also stimulate investment, which hampers population growth. Because population growth crowds out labor supply, production of capital-intensive dirty goods first increases and then decreases. This yields a typical environmental Kuznets path: pollution increases at the earlier stages but decreases at the later stages of development.     

The variance of population characteristics in stable populations, with applications to the distribution of income

Summary Stable population theory has recently been used to analyse the effects of changes in fertility and mortality on economic variables such as income per head. In this paper more general results are derived to describe the effects of changing vital rates on the variance and higher moments of the distribution of some age-dependent variable. Simple analytical expressions are derived which decompose the effects of changes in age structure into the effects on inter-cohort and intra-cohort variance. The results are easily applied to standard measures of the distribution of income. By combining the analytical results with actual age profiles of income and income variance from the United States and Brazil it is observed that both the magnitude and direction of the effects of population growth on measured inequality are sensitive to the specific age profiles used. The most surprising result is that the Brazilian age profiles suggest that higher growth rates may actually reduce measured inequality, although the effect is relatively small.     

Controlling population growth in Sri Lanka: perceptions,policies and strategies

Sri Lanka has been an oft-cited example in the demographic literature of developing countries over the past 4 decades. Despite its low level of per capita income, Sri Lanka has managed to achieve the lowest level of fertility in South Asia. Sri Lanka's population policies, especially with regard to fertility, have been rated as strong by some writers. The evolution of policies on population growth in Sri Lanka is described in the following sections: the problem of population growth, strategies for controlling population growth, the period of indirect government participation from 1948 to 1965, policy change during 1965-77, 1977 as the beginning of a new era of increasing government commitment to domestic population polices, and strategy changes from 1989 onwards. During this current, most recent, phase of population policy in Sri Lanka, the government has focused upon satisfying the demand for various family planning methods, demand which has been created by a well-promoted fertility control program during the preceding phases of policy implementation. Greater emphasis is simultaneously being given to improving reproductive health.     

The social effect of population growth in the periurban region: The case of Adelaide

The forces driving periurban population growth and change vary, resulting in different scales of periurban development, and local differences will undoubtedly modify the social effect of population growth in the periurban zone. The aim of this paper is to assess the effect of recent population growth on the social structure of periurban communities. Drawing on results from surveys of migration to three study areas in the periurban region of Adelaide (South Australia), the paper examines the perceptions of recent migrants as distinct from the established residents, focusing on three key aspects associated with population growth: social integration, satisfaction and identification with the local area and local commitment.     

The narrowing sex differential in life expectancy in high-income populations: effects of differences in the age pattern of mortality

Using data from the Human Mortality Database for 29 high-income national populations (1751-2004), we review trends in the sex differential in e(0). The widening of this gap during most of the 1900s was due largely to a slower mortality decline for males than females, which previous studies attributed to behavioural factors (e.g., smoking). More recently, the gap began to narrow in most countries, and researchers tried to explain this reversal with the same factors. However, our decomposition analysis reveals that, for the majority of countries, the recent narrowing is due primarily to sex differences in the age pattern of mortality rather than declining sex ratios in mortality: the same rate of mortality decline produces smaller gains in e(0) for women than for men because women's deaths are less dispersed across age (i.e., survivorship is more rectangular).     

The narrowing sex differential in life expectancy in high-income populations: Effects of differences in the age pattern of mortality

Using data from the Human Mortality Database for 29 high-income national populations (1751–2004), we review trends in the sex differential in e(0). The widening of this gap during most of the 1900s was due largely to a slower mortality decline for males than females, which previous studies attributed to behavioural factors (e.g., smoking). More recently, the gap began to narrow in most countries, and researchers tried to explain this reversal with the same factors. However, our decomposition analysis reveals that, for the majority of countries, the recent narrowing is due primarily to sex differences in the age pattern of mortality rather than declining sex ratios in mortality: the same rate of mortality decline produces smaller gains in e(0) for women than for men because women's deaths are less dispersed across age (i.e., survivorship is more rectangular).     

The greenhouse gas methane (CH4): Sources and sinks,the impact of population growth,possible interventions

Methane (CH₄) is one of the trace gases in the atmosphere that is considered to play a major role in what is called the greenhouse effect. There are six major sources of atmospheric methane: emission from anaerobic decomposition in (1) natural wetlands; (2) paddy rice fields; (3) emission from livestock production systems (including intrinsic fermentation and animal waste); (4) biomass burning (including forest fires, charcoal combustion, and firewood burning); (5) anaerobic decomposition of organic waste in landfills; and (6) fossil methane emission during the exploration and transport of fossil fuels. Obviously, human activities play a major role in increasing methane emissions from most of these sources. Especially the worldwide expansion of paddy rice cultivation, livestock production and fossil fuel exploration have increased the methane concentration in the atmosphere. Several data sets help estimate atmospheric methane concentration up to 160,000 years back. Major sources and sinks of present-day methane emission and their relative contribution to the global methane balance demonstrate great uncertainties in the identification and quantification of individual sources and sinks. Most recent methane projections of the Intergovernmental Panel on Climate Change (IPCC) for 2025 and 2100 are discussed and used to estimate the contribution of population growth to future methane emission. Finally the paper discusses options and restrictions of reducing anthropogenic methane emissions to the atmosphere.     

Capital accumulation,aspiration adjustment,and population growth: limit cycles in an Easterlin-type model

"One of the recent interesting hypotheses of population growth is due to Easterlin who suggests the possibility of self-generating fluctuations in birth numbers. The present paper tries to answer the question whether feedback mechanisms produce persistent oscillations in population growth. A system of two nonlinear differential equations for the per capita capital stock and the aspiration level is studied by a phase portrait analysis. Using the Poincare-Bendixson theorem we derive sufficient conditions for the existence of a stable limit cycle." (SUMMARY IN FRE)     

Aggregate population and economic growth correlations: The role of the components of demographic change

The results of recent correlations showing a negative impact of population growth on economic development in cross-country data for the 1980s, versus “nonsignificant” correlations widely found for the 1960s and 1970s, are examined with contemporaneous and lagged components of demographic change, convergence-type economic modeling, and several statistical frameworks. The separate impacts of births and deaths are found to be notable but offsetting in the earlier periods. In contrast, the short-run costs (benefits) of births (mortality reduction) increase (decrease) significantly in the 1980s, and the favorable labor-force impacts of past births are not fully offsetting.     

Child mortality and reproductive behaviour in German village populations in the past: A micro-level analysis of the replacement effect

Abstract Reproductive histories of couples married during the eighteenth and nineteenth centuries in a sample of 14 German villages are analysed in order to answer several questions regarding the relationship between child mortality and reproductive behaviour. An effort is made through selection of cases and use of multiple classification analysis to eliminate or control non-volitional or otherwise confounding influences on the relationship between a couple's experience with child mortality and their fertility. The results do not provide a decisive answer to the question of whether, under a regime of otherwise presumed natural fertility, previous experience of child mortality affected subsequent reproductive behaviour. The evidence was much clearer in indicating that behaviour consistent with replacement efforts emerged or strengthened as family limitation spread. Finally, the results indicated that though it was not necessary for overall child mortality to decline before family limitation practices were adopted, couples with the most favourable child mortality experience were most likely to practise family limitation and to reduce their fertility. Child mortality appeared at least to impede, if not totally prevent, efforts to reduce the number of children ever born or to cease childbearing at an earlier age or at a given parity.     

Aids and population growth in sub-Saharan Africa: Assessing the sensitivity of projections

Despite different models to project the course of the AIDS pandemic and a scarcity of data to provide standard input parameters for those models, a limited consensus emerges from distinct sets of population projections. In sub-Saharan Africa, population growth rates are projected to remain positive in spite of the pandemic over the next few decades. To investigate this conclusion, alternative projections of an HIV/AIDS epidemic and its related mortality are first produced from different sets of input parameters and assumptions. Their incorporation into the population projections of a fast-growing country illustrates the robustness of projected population growth rates under very different scenarios of the future epidemic but with the common assumption that it will not affect the mortality of the uninfected population, fertility nor migration. This paper then shows that the projected growth rates are much less robust when interactions between the epidemic and the demographic regime are allowed and identifies several potential mechanisms for such interactions. In particular, it suggests that improving our confidence in the medium-term projections of the demographic impact of AIDS in the region requires less a refinement of the projections of the epidemic than a better understanding of its impact on the timing of the postulated fertility decline.