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Summary Article: demography
from The Dictionary of Human Geography

The science of human populations. For much of the preceding 400 years, the field has concerned itself with the size, distribution and composition of populations, and how changes in these are connected with the three population processes of mortality, fertility and migration (Greenhalgh, 1996). While formal demography has developed mathematical and actuarial techniques to model and project changes in population (see life table; population projection), the interdisciplinary field of population studies examines demographic change within its broader societal setting and makes use of a wide range of approaches (see, e.g., historical demography; life course). Despite its keen interest in population distribution, its interdisciplinary niche and its strong connections with sociology and economics, demography has had a relatively limited engagement with geography. Although the development of population geography between the 1960s and the 1980s and the growth of spatial demography drew attention to the study of mortality, fertility and particularly migration, many geographical analyses of issues including poverty, gender roles, social exclusion, urbanization and environmental degradation underplay population factors (but for a recent exception, see Gould, 2005).

Descriptions of changes in population size and distribution make use of empirical data on deaths, births, moves and the ages at which these events occur, mostly obtained from population censuses, social surveys or registers of population. Population growth within an area is most simply expressed through the balancing equation as follows:

where P is the population size, B is births, D is deaths, I is in-migrants to an area, E is outmigrants from an area, t2 is time 2, t1 is time 1 in the past, and t1 – t2 is the time interval between time 1 and time 2. Knowledge of the ages at which vital events occur allows age-specific rates to be used to create synthetic or model populations that approximate actual age compositions of populations, and may be used to project future population scenarios (see population projection). Such stable population theory is at the basis of life tables that are used to calculate life expectancy by age, the number of survivors by age, and thus the impact of the three population processes upon the age structure, and vice versa. Armed with such data, research on changes in population growth and distribution has centred on efforts to build, critique and extend the demographic transition model; for example, through work on differentials in mortality, the onset of fertility decline and, more recently, its recovery (Bongaarts, 2002; Case and Paxson, 2005).

The field has long enjoyed an extremely close – some have argued, too close – relationship with social policy, whether at the international scale such as the League of Nations’ commissioning of the Office of Population Research’s work on transition theory in the 1940s, or in informing the US administration’s laissez-faire position on family planning at the 1984 International Conference on Population and Development, or more recently in assessing the impact of immigration policy or welfare reform measures upon the life chances of low-income family members (Büche and Frick, 2005). A good deal of research effort continues to debate new dimensions of the population–resource–well-being nexus in light of the likely global diffusion of low fertility and ageing, and the short-termism of replacement migration policies (Meyerson, 2001). Connected to this, studies in family demography describe factors behind changes in the timing and nature of decisions about marriage and partnering, divorce and household dissolution, leaving and rejoining the parental home, cohabitation, and transitioning from full-time to part-time and unpaid work (Holdsworth and Elliot, 2001). The diversification and plurality of households is a theme in work on, for example, mixed marriages, and variations in intergenerational relations and resource flows by class, gender, race and ethnicity (Gershuny, 2000). Many analyses link family demography to well-being, with an increasing emphasis upon children (Eloundou-Enyegue, 2004). Applied research includes the development of geographical informational systems and geodemographic techniques; both are used by marketing firms to target launch new products and design sales areas, and by local authorities to deliver services more efficiently.

Suggested reading

Full bibliography is available here.

Greenhalgh (1995)

Kent and Haub (2005)

Lutz, Sanderson and Scherbov (2004).

Adrian Bailey
Professor of Migration Studies
School of Geography, University of Leeds, UK
© 2009 by Blackwell Publishing Ltd except for editorial material and organization, © 2009 Derek Gregory, Ron Johnston, Geraldine Pratt, Michael J. Watts, and Sarah Whatmore

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