arithmetic density
The total number of people per unit of land; also called crude density.
physiological density
the total number of people per unit of arable land
sex ratio
the proportion of males to females in a population
dependency ratio
the number of people in a dependent age group (under age 15 or over the age of 65) divided by the number of people in the working-age group (ages 15 to 64), multiplied by 100
total fertility rate (TFR)
average number of children one woman in a given country or region will have during her childbearing years, which are ages 15 to 49.
life expectancy
an average number of years a person is expected to live
crude birth rate (CBR)
the number of births in a given year per 1,000 people in a given population
doubling time
the number of years in which a population growing at a certain rate will double.
population pyramid
a graph that shows the age-sex distribution of a given population
crude death rate (CDR)
the number of deaths in a given year per 1,000 people in a given population
natural increase rate (NIR/RNI)
rate at which a population grows as the result of the difference between the crude birth rate and the crude death rate
overpopulation
a term used to describe the condition in which population growth outstrips the resources needed to support life
EPIDEMIOLOGICAL Transition Model (ETM)
a model that describes changes in fertility, mortality, life expectancy, and population age distribution, largely as a result of changes in causes of death
Demographic Transition Model (DTM)
A model that represents shifts in the growth of the world's population, based on population trends related to birth rate and death rate
pronatalist
describing attitudes or policies that encourage childbearing as a means of spurring population growth
gravity model
a model that predicts the interaction between two or more places
forced migration
type of migration in which people are compelled to move by economic, political, environmental, or cultural factors
step migration
series of smaller moves to get to the ultimate destination
chain migration
type of migration in which people move to a location because others from their community have previously migrated there
transhumance
the movement of herds between pastures at cooler, higher elevations during the summer months and lower elevations during the winter
internally displaced person (IDP)
person who has been forced to flee his or her home but remains within the country's borders
interregional migration
movement from one region of the country to another
quota
limit on the number of immigrants allowed into the country
remittances
money earned by an emigrant abroad and sent back to his or her home country
brain drain
the loss of trained or educated people to the lure of work in another—often richer—country