DEMOGRAPHY
The study of the size, composition, distribution and changes in human populations.LIFE SPAN: The maximum length of life possible in a particular species.
LIFE EXPECTANCY: The number of years that the average newborn in a particular population
can be expected to live.
FECUNDITY: The potential number of children that could be born to a woman of child-bearing
age.
FERTILITY: The actual number of children that are born to women of child-bearing age.
CRUDE BIRTH RATE:
The annual number of births per 1000 members of a population.
FERTILITY RATE:
The annual number of births per 1000 women of child-bearing age (ages 15-44).
CRUDE DEATH RATE:
The annual number of deaths per 1000 members of a population.
INFANT MORTALITY RATE:
The number of children who die within the first year of life per 1000 members of live
births in a given year..
COHORT: A category of people who are born in the same period such as a period of one or 5 years.
Population composition shows:
What is future age/sex ratios based on birth and death rates, important for social planning;
What is the "dependency ratio"(i.e. the proportion of the population who are dependent on others for economic support (e.g. children, students, aged, "stay-at-home" adults);
How large is the potential labor force;
How many young people are of marriageable age and what is the sex ratio (i.e. # of males per 100 females)
What special needs can be projected re: schools, care for the elderly, integration of immigrant populations
What is the distribution of the population within the country and by economic sectors;
Are the resources of the society sufficient to support the size of population or is there pressure for
a) expansion (including "annexing" other territory
b) emigration
c) reducing population growth
Population increases to the limits or the food supply
Food supply grows at an arithmetic rate (i.e. 1+1=2, 2+1=3, 3+1=4, etc.) while population grows at an
exponential rate (2x2=4, 4x4=16, 16x16=256, etc.)
Population will outrun the food supply
Natural "checks" on size of population are:
- famine
- war
- disease
LIFE EXPECTANCY IN THE UNITED STATES
BY YEAR, RACE AND SEX: 1900-1990
Life Expectancy
White Black
Year Male Female Male Female
1900 46.6 48.7 32.5 33.5
1910 48.6 52.0 33.8 37.5
1920 54.4 55.6 45.5 45.2
1930 59.7 63.5 47.3 49.2
1940 62.1 66.6 51.5 54.9
1950 66.5 72.2 59.1 62.9
1960 67.4 74.1 61.1 66.3
1970 68.0 75.6 61.3 69.4
1980 70.7 78.1 65 .3 73.6
1990 73.4 80.2 67.7 75.0
Total 1996 76.0
At age 65 14.9 18.6 13.4 16.9
SELECTED WORLD POPULATION STATISTICS, 1996
Country Crude Life Infant Fertility Growth
Birth Expec Mortality Rate Rate (%)
Rate tancy Rate (1990-00)
States 14.8 76.0 6.7 2.06 1.0
Bangladesh 30.5 55.9 102.3 3.57 1.8.
Peoples Rep
of China 17.0 69.6 39.6 1.81 1.0
Haiti 38.2 49.3 103.8 5.69 1.8
Italy 7.9 78.1 6.9 1.27 Zero
Mali 51.4 46.8 102.7 7.25 2.8
Mexico 26.2 73.7 25.0 3.03 1.9
Somalia 44.2 55.5 121.1 7.01 2.7
Yemen 45.2 59.6 71.5 7.29 3.9
Bosnia &
Herzegovina -5.1
World 1.4
STAGE ONE:
Birth rates are high but balanced by high death rates. Population is stable.
STAGE TWO:
Death rates are reduced. Birth rates remain high. Population grows rapidly.
STAGE THREE:
Death rates remain low. Birth rates drop to balance with death rates. Population is stable.
SECOND DEMOGRAPHIC TRANSITION:
Birth rates drop further, below replacement level. Population declines.
WHY RELUCTANCE IN LESS INDUSTRIALIZED SOCIETIES TO ACCEPT POPULATION
CONTROL
+ Lack of kinowledge about effective birth control measures (probably least important
+ Poverty: cannot afford most effective birth control devices and measures
+ Cultural values favoring large families:
- "Be fruitful and multiply", i.e divine mandate to have children
- Religious beliefs prohibiting artificial contraception
- Emphasis on children as a sign of male virility
- Emphasis on women's role as mothers (especially of sons)
+ Economic factors
- children as economic assets for total family income
- children as "social security" for parents in their old age.