Demography

• de jure method is done when people are assigned to the place where they usually live regardless of where they are at the time of census.
• de facto method is done when the people are assigned to the place where they are physically present at the time of the census regardless of their usual place of residence.
• Registration systems such as those collected by the civil registrar’s office deal with recording vital events in the community. 
• Vital Events refer to births, deaths, marriages, divorces, and the like. 

  • They typically collect information about families or households, as well as about such individual characteristics as
  • Age,
  • Sex,
  • marital status,
  • literacy/education,
  • employment status and occupation, and
  • geographical location.
• Population - study of the character, number, and distribution of living organisms residing in or migrating through particular places. 
• Principal uses of population data in health administration:

  • Computation of vital and health statistics rates and ratios
  • Setting up coverage of activities
  • Setting up norms for assignment of health facilities, staff, and funds
• Continuous Population Registration involves:

  • Registering births, deaths, emigration, and immigration
  • Making necessary additions and subtractions to the existing population
• Estimating the number of population in a smaller area involves:

  • Counting the number of houses
  • For every ten houses, conducting a census
  • Based on the censused household, estimating the average occupancy per house
  • Multiplying this figure by the number of households
• Mathematical Estimates 

  • Maybe done by means of arithmetic and geometric increase method
  • (census year b / census years) / # of years between year a and b
• Arithmetic Increase Method

  • assumed that the population increases at a constant amount per year
  • difference between the last two censuses is taken and then divided by the number of year between them to get the average amount of population increase per year
• Geometric Increase Method

  • assume that population increases at a constant rate per year
  • determination of annual rate of population change
• Crude birth rate:

  • The annual number of live births per 1,000 people
• General fertility rate:

  • The annual number of live births per 1,000 women of childbearing age (often taken to be from 15 to 49 years old, but sometimes from 15 to 44)
• Age-specific fertility rates:

  • The annual number of live births per 1,000 women in particular age groups (usually age 15-19, 20-24 etc.)
• Crude death rate:

  • The annual number of deaths per 1,000 people
• Infant mortality rate:

  • The annual number of deaths of children less than 1 year old per 1,000 live births
• Expectation of life:

  • The number of years that an individual at a given age could expect to live at present mortality levels
• Total fertility rate:

  • The number of live births per woman completing her reproductive life, if her childbearing at each age reflected current age-specific fertility rates
• Replacement level fertility:

  • The average number of children a woman must have to replace herself with a daughter in the next generation
• • The total fertility rate, the number of live births per woman completing her reproductive life, if her childbearing at each age reflected current age-specific fertility rates.
• • The replacement level fertility is the average number of children a woman must have to replace herself with a daughter in the next generation.
• • A stable population does not necessarily remain fixed in size, it can be expanding or shrinking.
• • The gross reproduction rate, the number of daughters who would be born to a woman completing her reproductive life at current age-specific fertility rates.
• • The net reproduction ratio is the expected number of daughters, per newborn prospective mother, who may or may not survive to and through the ages of childbearing.
• • A stable population, one that has had constant crude birth and death rates for such a long time that the percentage of people in every age class remains constant, or equivalently, the population pyramid has an unchanging structure.
• • A stationary population, one that is both stable and unchanging in size (the difference between crude birth rate and crude death rate is zero).
• Demography

  • is the statistical study of the human population.
  • It can be a very general science that can be applied to any kind of dynamic human population, that is, one that changes over time or space.
  • It encompasses the study of the size, structure, and distribution of these populations, and the changes in them in response to birth, migration, aging, and death
• Census

  • A census is the other common direct method of collecting demographic data.
  • conducted by a national government
  • attempts to enumerate every person in a country. However, in contrast to vital statistics data, which are typically collected continuously and summarized on an annual basis, censuses typically occur only every 10 years or so and thus are not usually the best source of data on births and deaths.
  • Analyses are conducted after a census to estimate how much over or undercounting took place.
• Fertility – involves the number of children that women have and is to be contrasted with fecundity (a woman's childbearing potential).
• Mortality – study of the causes, consequences, and measurement of processes affecting death to members of the population
• Migration – refers to the movement of persons from an origin place to a destination place across some pre-defined, political boundary.
• Natural increase is simply the difference between the number of births and the number of death occurring in a population in a specified period of time
• Rate of Natural increase is the difference between the CBR and the CDR occurring in a population in a specified period of time
• Absolute increase per year - Measures the number of people that are added to the population per year.
• Relative increase - Is the actual difference between the two census counts expressed in percent relative to the population size made during an earlier census.
• Sex composition

  • To describe the sex composition of the population, the nurse computes for the sex ratio.
  • The sex ratio compares the number of males to the number of females in the population
• Age Composition : Median age 

  • divides the population into two equal parts, 
  • so, if the median age is said to be 19 years old, it means half of the population belongs to 19 years and above, while the other half belongs to ages below 19 years old.
• Age Composition : Dependency Ratio

  • compares the number of economically dependent people with the economically productive group in the population, 
  • economically dependent are those who belong to the 0-14 and 65 above age groups, considered to be economically productive 
  • are those within the 15- 64 age group, The dependency ratio represents the number of economically dependent for every 100 economically productive.
• Age and Sex composition can be described at the same time using a population pyramid. It is a graphical presentation of the age and sex composition of the population.
• Human demography (branch of sociology) is the study of the attributes of and changes in the aggregate number of people residing in particular communities around the world and their causes.