Demography Notes

Definition of Demography

  • Demography: A statistical and mathematical study of human populations, focusing on:
    • Population size.
    • Composition.
    • Spatial distribution.
    • Changes over time influenced by five key processes: fertility, mortality, marriage, migration, and social mobility.

Sources of Demographic Data

  • Common sources include:
    • National census (e.g., PSA in the Philippines).
    • Civil registration systems for marriage.
    • Sample surveys.

Etymology of Demography

  • Derived from two Greek words:
    • Demos: People.
    • Graphos: Drawing.

Types of Demography

1. Static Demography
  • Examines the structure of communities at a specific time.
    • Analyzes population anatomy, size, density, and composition.
2. Dynamic Demography
  • Focuses on how populations change over time.
    • Looks at processes like mortality, fertility, and migration.

Population Characteristics

  • Key components of population studies include:
    • Size: Total number of persons in a specified area.
    • Structure: Distribution among age and sex (e.g., number of women below the age of 30).
    • Distribution: Arrangement of people in space at a given time (e.g., rural vs. urban).

Influences on Population Dynamics

  • Factors influencing population changes:
    • Fertility (Natality): Ability to conceive.
    • Mortality: Death rates in a population.
    • Marriage: Average age at first marriage affecting birth rates.
    • Migration: Movement from one geographical area to another affecting local populations.
    • Social Mobility: Changes in social status affecting demographics.

Fertility and Mortality

  • Fertility: Ability of individuals to bear children.
  • Mortality: Measurement of death rates within a population (e.g., crude death rate).

Migration

  • Involves the movement of individuals within or across countries.
  • Example: Influx of Indian migrants to the Philippines.

Childbearing Considerations

  • Ideal age for childbearing is 18-32 years, after which risks increase.
  • Early childbearing can boost population growth; delaying impacts demographic structures.

Demographic Transition Model (DTM)

  1. High Stationary Stage:

    • High birth and death rates.
    • Population remains stable.

  2. Early Expanding Stage:

    • Birth rates are stable, death rates start declining, resulting in population growth.

  3. Late Expanding Stage:

    • Declining death rates and falling birth rates, leading to continued population growth.

  4. Low Stationary Stage:

    • Low birth and death rates stabilize population.
    • Example: Japan shows stability due to low rates.

  5. Declining Stage:

    • Birth rates lower than death rates, resulting in population decline, also evident in Japan.

Conclusion

  • Demography is crucial for understanding human population changes and their implications on society and policy-making. It integrates statistical analysis with demographic theories to interpret population dynamics effectively.