Demography

• Demography


  The empirical, statistical and mathematical study of human population
• Demography


  The mathematical and statistical study of the size composition and spatial distribution of human populations and of changes over time in these aspects through the operation of five processes of: Fertility, Marriage, Mortality, Social Mobility, Migration

  
• De jure method


  Assigns individuals to the place of their usual residence regardless of where they were actually enumerated during the census
• De facto method


  Where people are allocated to the areas where they were physically present at the census date regardless of where they usually live
• Features of a National Census
• Information Obtained in a Census
• Population Size


  Pertains to: 1. Actual population size, 2. Changes or trends in population size - Absolute changes, Rates of changes, Trends

  
• Distribution of the Population

  Refers to the location of the population in geographic subdivisions of a given area - Continents, countries, states, Urban or rural areas
• Population Composition


  Pertains to measurable characteristics of the population - Age, Sex, Marital status, Occupation, Religion

  
• Sex Ratio


  Compares the number of males to the number of females
• Demographics of Philippines 2022

  
• Sex Structure


  Compares the sex ratio across different categories/ levels of another characteristic
• Median Age


  The value which cuts-off the upper 50% and lower 50% of the ages of the population, Indicates whether the population is young or old
• Philippines's median age is 24.5 against a global value of 30.3 years

  
• Age-Dependency Ratio


  Provides an index of age-induced economic drain on manpower resources, Three types: Youth, Elderly, Total
• Youth Dependency Ratio


  Population ages 0-15 divided by the population ages 16-64
• Elderly Dependency Ratio


  Population ages 65-plus divided by the population ages 16-64
• Total Dependency Ratio


  Sum of the youth and old-age population divided by the population ages 16-64
• Dependency Ratio does not take into account labor force participation rates by age group
• Factors Affecting Age Composition

  • Fertility, Urban – rural differences, Peace and order situation, Cultural practices
• In 2022, population aged 15-64 years for Philippines was 64.2 %. Population aged 15-64 years of Philippines increased from 51.5 % in 1973 to 64.2 % in 2022 growing at an average annual rate of 0.45%.

  
• Population Pyramid


  A graphical presentation of the age and sex composition of the population, Enables one to explain and describe the demographic trends of the population in the past

  
• Constructing a Population Pyramid

  Compute the percentage of the population falling in each age-sex group, 2. Let each age group be represented by a horizontal bar, 3. The bars for the males are drawn on the left side of the central vertical axis and the bar for the females on the right side

  
• Population aged 15-64 years

  Economically productive
• Population Pyramid


  • A graphical presentation of the age and sex composition of the population
  • Enables one to explain and describe the demographic trends of the population in the past

  
• Constructing a Population Pyramid

  1. Compute the percentage of the population falling in each age-sex group

  2. Let each age group be represented by a horizontal bar

  3. The bars for the males are drawn on the left side of the central vertical axis and the bar for the females on the right side

  4. The length of each bar corresponds to the percent (%) of the population falling in the specific age and sex group being plotted

  
• Determinants of the Sex Composition of a Population

  • Sex ratio at birth
  • Differences between sexes in death rates
  • Geographic, economic conditions
  • Occupation
  • Differences between sexes in net migration rates
• Generalizations of the Sex Composition of a Population

  • Sex ratio at birth
  • Age specific mortality rates usually greater among males, the sex ratio decreases with age, eventually falling below 100
  • Sex ratio is generally higher in rural than in urban areas
  • Frontier communities and colonies generally have higher sex ratio
• Consequences of Age and Sex Structure


  • Consumption patterns
  • Death rate
  • Rates and patterns of migration
  • Probabilities of marriage for men and women
  • Power structure
• Life Expectancy at birth

  The average number of years a newly born infant is expected to live under the mortality conditions for a given year
• • Life expectancy: 71.53 years (2022 est)
  • Male: 68.7 years
  • Female: 74.7 years (2022 est.)
• Natural Increase


  The difference between the number of births and the number of deaths which occurred
• Rate of Natural Increase

  The difference between the crude birth rate and the crude death rate of a specific population within a specified time period, usually a year
• Absolute increase per year (b)


  Measures the average number of people added to the population each year
• Relative Increase


  The actual difference (i.e., the absolute increase) between two census counts expressed in percent of the initial population size
• Annual Rate of Growth


  Utilizes results of two census counts to quantify the amount of change in population size during a specified time period, assuming the population is increasing at a constant rate per year
• Purposes of Estimates and Projections:

  1. For analysis of various trends;

  2. For measuring shifts in population;

  3. For determining allocation of public funds or political representation in the government'

  4. For planning
• Types of Estimates and Projections

  • According to detail desired: Total population vs. Subgroups, Population by selected characteristics (e.g., age, sex)

  According to time reference: intercensal estimates, postcensal estimates, projections

  According to method (or assumption) used: component, Arithmetic, Geometric, Exponential

  
• Intercensal estimates


  Refer to population estimates made on any date intermediate to two censuses and take the results of these census into account

  
• Postcensal estimates


  Estimates of population size on any date in the past or during a current date following a census; use the results of the most recent census and possibly earlier censuses into account, but not later censuses