Demography in Public Health: Analyzing Global Population Trends

Demography in Public Health and Medicine: Global Population Issues

Defining Demography

Demography is the statistical study of human populations based on: size, density, distribution, and vital statistics.

Importance and Application of Demographic Data

Demographic data provides essential information used for:

• Health service planning and health care provision.
• Scientific and medical research.
• Analysis of health status and population state.

Populations change through three fundamental processes:

• Fertility (births)
• Mortality (deaths)
• Migration (movement)

Methods of Data Collection

Demographic data is collected using both direct and indirect methods.

• Direct Methods:

  Data comes from vital statistics registries that track all births and deaths, as well as certain changes in legal status such as marriage, divorce, and migration (registration of place of residence).

  • The Census can also be used as a direct method.
• Indirect Methods:

  Used whenever full data are not available, typically in developing countries or for historical demographics.

  • Examples include the sister method, where survey researchers ask women how many of their sisters have died or had children, and at what age.

Demographic Statistics and Analysis

The main method of research involves analyzing demographic statistics, categorized into Statics and Dynamics:

• Demographic Statics: Focuses on the state of the population at a specific point in time.
  • Number of inhabitants.
  • Distribution: Population composition (structure) by sex and by age.
• Demographic Dynamics: Focuses on population mobility and change over time.
  • Natural changes: Births, deaths.
  • Mechanical changes: Movement, migration.
  • Socio-legal changes: Marriages, divorces, abortions.

Primary Information Sources

• Number of inhabitants – determined by a “count.”
• National population census – typically conducted every 10 years.
• Microcensus and balance method (estimation techniques).
• National registers – central register of citizens.
• Sample surveys.

The Median State of Population (or mid-year population) is used very often in statistical calculations.

Global Population Challenges

Population problems vary significantly between developed and developing regions:

Issues in the Developed World

• Low natality (birth rates).
• Population ageing (approximately 20% of the population is over 60 years old).
• Prolonged life expectancy (LE).
• Low Infant Mortality Rate (IMR) – e.g., 3 per 1,000 live births.
• Low fertility rates – e.g., 1.2 (as seen in the Czech Republic).

Issues in the Developing World

• Start of population ageing (a transitional phase).
• High fertility rates.
• High Infant Mortality Rate (IMR) coupled with lower Life Expectancy (LE).

  Note: As the IMR decreases, LE typically increases.