31. Demography: definition, methods, data sources

From greek.doctor
  • Demography is the scientific study of the determinants and consequences of changes in human population
  • You can only enter a population by birth or migration, and you can only leave it by death or migration
    • Therefore, fertility, mortality, and migration are important in the study of demographics
    • Keeping record of birth and death is simple; migration is not always registered and therefore more difficult to keep record of
  • Variables in demography
    • Age
    • Gender
    • Income
    • Occupation
    • Health service use
    • Geographic location
    • Geographic density
  • T.R. Malthus – first person to draw attention to fertility and mortality
    • He postulated that population tends to grow geometrically while food supply grew only arithmetically (i.e., the population grows much faster than the food supply)
      • This is sometimes called the Malthusian trap
    • Because of the Malthusian trap, war, disease, hunger would control the population growth
    • However, the industrial revolution made an exponential growth in food supply possible, bypassing the Malthusian trap and allowing for a population explosion
  • Data sources
    • Vital statistics registries
      • Vital statistics registries continuously collect information of demographic events like birth, deaths, marriages, etc., as they occur
    • Census
      • A census occurs every 10 years and collects demographic and other data at that point in time
      • While vital statistics registries are continuously collected, a census occurs only every 10 years
      • The collection of this data can occur by sending out questionnaires in the mail, or by collecting data from digital registers
    • Direct data can be collected from registries of vital statistics or censuses
      • These registries track all births, deaths, marriage, divorce, migration
      • In developed countries these are the best sources
    • Indirect data can be collected by asking women how many sisters have died or had children, asking people about siblings, parents, etc.
      • From this, researchers can indirectly estimate data for the whole population
      • Necessary in countries which don’t keep registries