Aphug

Population distribution

The arrangement of people across Earth's surface

Population density

The number of people living in a given area.

Arithmetic density

Total population ÷ total land area

Physiological density

Total population ÷ amount of arable land

Agricultural density

Number of farmers ÷ amount of arable land

Arable land

Land that is suitable for growing crops.

Ecumene

The portion of Earth's surface permanently inhabited by people

Concentration

How closely or widely people are spread across an area.

Clustered concentration

Population is grouped closely together.

Dispersed concentration

Population is spread out over a larger area.

Physical factors

Natural characteristics that influence where people live, such as climate, landforms, and water.

Human factors

Human-created characteristics that influence population distribution, such as jobs, transportation, and political conditions

Carrying capacity

The largest population an environment can sustainably support

Natural increase

Population growth caused by births minus deaths.

Crude birth rate (CBR)

Number of live births per 1,000 people per year.

Crude death rate (CDR)

Number of deaths per 1,000 people per year.

Natural increase rate (NIR)

Rate at which a population grows from natural increase.

Doubling time

The amount of time needed for a population to double

Population growth rate

The rate at which a population increases or decreases

Population distribution

Where people are located and how they are spread out.

Overpopulation

A situation where a population exceeds the resources available to support it.

Underpopulation

A population that is smaller than the available resources could support.

Population pressure

Pressure placed on resources and the environment as population increases

Resource availability

The amount of resources available to support a population.

Population composition

The characteristics of a population, including age and sex.

Age-sex pyramid / population pyramid

A graph showing the age and sex structure of a population

Age structure

The percentage of people in different age groups

Sex ratio

The number of males for every 100 females in a population

Dependency ratio

The number of people who are too young or too old to work compared with the working-age population

Youth dependency ratio

The number of people under 15 compared with the working-age population.

Elderly dependency ratio

The number of people 65+ compared with the working-age population

Working-age population

People generally considered able to work, usually ages 15–64

Cohort

A group of people who share a particular characteristic, often having been born during the same period.

Baby boom

A period of unusually high birth rates

Baby bust

A period of declining birth rates following a baby boom

Gender

Socially constructed roles and expectations associated with sex

Sex-selective practices

Practices that favor one sex over another, such as sex-selective abortion.

Maternal mortality rate (MMR)

Number of women who die from pregnancy-related causes per 100,000 live births.

Infant mortality rate (IMR)

Number of infant deaths per 1,000 live births

Life expectancy

Average number of years a person is expected to live.

Fertility rate

Number of births relative to the number of women of childbearing age.

Total fertility rate (TFR)

Average number of children a woman is expected to have during her lifetime.

Aging population

A population with an increasing percentage of elderly people.

Elderly population

People generally 65 years and older.

Life expectancy

Average number of years a person is expected to live

Dependency ratio

Ratio comparing dependent populations with the working-age population.

Elderly dependency ratio

Number of elderly people compared with the working-age population.

Pension

Regular payment provided to people after they retire.

Social Security

Government program that provides financial support to eligible retirees and others.

Healthcare costs

Medical expenses that can increase as populations age.

Retirement age

The age at which people generally stop working and begin receiving retirement benefits.

Youth dependency ratio

Number of young dependents compared with the working-age population.

Population decline

A decrease in the total population of an area.

Replacement-level fertility

Fertility level needed for a population to replace itself, approximately 2.1 children per woman in developed countries

Zero population growth (ZPG)

population condition where births plus immigration approximately equal deaths plus emigration.

Anti-natalist policies

Government policies designed to reduce birth rates

Pro-natalist policies

Government policies designed to increase birth rates

Natural decrease

When the death rate is higher than the birth rate.

Migration

Movement of people from one place to another, which can affect the age structure of both places.