Demography Lecture Notes PDF

Lec.4 Dr. Shaymaa A. Majed DEMOGRAPHY Demography is defined as "the study of populations, especially with reference to size and density, fertility, mortality, growth, age distribution, migration, and vital statistics and t...

Lec.4 Dr. Shaymaa A. Majed DEMOGRAPHY Demography is defined as "the study of populations, especially with reference to size and density, fertility, mortality, growth, age distribution, migration, and vital statistics and the integration of all these with social and economic conditions" Vital statistics include births, deaths, population by age, sex, by location of residence, marital status, socioeconomic status, and migration. Birth data are derived from mandatory reporting of births and mortality data from compulsory death certificates. Other sources of data are population registries including marriage, divorce, adoption, immigration as well as economic and labor force statistics compiled by governmental agencies, census data, and data from special household surveys. These form the basic data sets for demographers. Demography measures trends over time of indices such as birth and death rates, rural-urban residential patterns, marriage and divorce rates and migrations, as well as social and economic conditions. Since public health deals with disease as it occurs in the population, the definition of populations and their characteristics is fundamental. A census is an enumeration of the population recording the identity of all persons in every residence at a specified time. The census provides important information on all members of the household, including age, date of birth, sex, occupation, national origin, marital status, income, relation to head of the household, literacy, education levels, and health status (e.g., permanent handicapping conditions). Other information on the home and its facilities include type of building, number of rooms, electricity, major home appliances (e.g., stove, refrigerator), toilet and bathroom facilities (e.g., bathtub, shower), car ownership and home heating (stove or central), food purchases, and spending on clothing, entertainment, and other consumption items. Usually census surveys are carried out to determine trends in important economic or demographic data such as family incomes, nutrition, employment, and other social indicators. Accuracy of such a complex and costly process cannot be 100%, but great care is taken to assure maximum response and standardization in interview methods and processing to assure precision. Despite its limitations, the census is accepted as the basis of statistical definition of a population. A demographic transition occurs when there is a substantive change in the age distribution of a population. Population growth is mainly affected by birth and death rates, although other factors such as migration, war, political chaos, famine, or natural disasters may affect population distribution. Changing population patterns also accompany economic development, a process known as demographic transition. This is often characterized by the following stages: 1. Traditional: high and balanced birth and death rates; 2. Transitional: falling death rates and sustained birth rates; 3. Low stationary: low and balanced birth and death rates; 4. Graying of the population: increased proportion of elderly as a result of decreasing birth and death rates, and increasing life expectancy; 5. Regression: migration or increasing death rates among young adults due to trauma, AIDS, early cardiovascular disease or war resulting in steady or declining longevity (demographic regression). Population Pyramid A population pyramid provides a graphic demonstration of the age and sex at a point in time. A country or region with a wide population base has a high birth rate and a large percentage of its population under age 15, usually accompanied by limited resources and is a formula for continued poverty. A population pyramid with a narrow base (i.e., few young people) and a growing elderly population will have a smaller work force to provide for the "dependent age" population (i.e., both the young and the old). With a smaller working age population to support these costs, adverse economic consequences may prejudice costly pension and health services. Other factors may also affect the population pyramid, for example, the loss of a large number of people during wartime. This loss affects a particular age-sex group as well as fertility patterns both during and after the war, for example, a post-war "baby boom."