Population Composition - AP Human Geography

A wide base in a population pyramid indicates a high birth rate. More births mean larger younger age cohorts.

Sex Ratio = $\frac{\text{Number of Males}}{\text{Number of Females}} \times 100$. Expressed as males per 100 females.

The sex ratio is the ratio of males to females in a population. Compares the number of males to females in a population.

A narrow top suggests a smaller elderly population, indicating lower life expectancy. Fewer elderly indicates shorter average lifespan.

Population composition refers to the structure of a population in terms of age, sex, and other properties. This definition includes key demographic characteristics that describe population structure.

The dependency ratio is the ratio of dependents (aged 0-14 and 65+) to the working-age population (15-64). Measures economic burden on the working-age population.

A population pyramid is a graphical illustration that shows the distribution of various age groups in a population. Visual representation showing age cohorts as horizontal bars.

Child Dependency Ratio = $\frac{\text{Population 0-14}}{\text{Population 15-64}} \times 100$. Measures burden of children on working-age population.

A youthful population means a high proportion of the population is under age 15. Large proportion of young people indicates high birth rates.

Age-sex structure. Technical term for population composition by age and gender.

A high dependency ratio indicates a larger proportion of dependents compared to the working-age population. Creates economic strain on the productive population.

A bulge indicates a demographic event, such as a baby boom or influx of migrants. Shows significant demographic events affecting specific age cohorts.

Stage 3 of the demographic transition model. Later industrial stage when family size preferences change.

The median age indicates the age at which half the population is older and half is younger. Divides population into equal halves by age.

Elderly Support Ratio = $\frac{\text{Working-age population}}{\text{Population 65+}}$. Shows how many working people support each elderly person.

Life expectancy is the average number of years a newborn is expected to live under current mortality levels. Reflects overall health conditions and quality of life.

The infant mortality rate is the number of infant deaths per 1,000 live births in a year. Key indicator of healthcare quality and child survival.

Sex Ratio = $\frac{1040}{1000} \times 100 = 104$. 104 males per 100 females in this population.

Stage 2 of the demographic transition model. Early industrial stage when healthcare improves but births remain high.

Stage 1 of the demographic transition model. Pre-industrial stage with high mortality balancing high fertility.

Dependency Ratio = $\frac{200}{800} \times 100 = 25$. 25 dependents per 100 working-age individuals.

A rectangular shape indicates a stable population with low birth and death rates. Characteristic of developed countries with controlled population growth.

Natural increase rate is the difference between the crude birth rate and the crude death rate. Shows net population change from births and deaths only.

The crude birth rate is the number of live births per 1,000 people in a population per year. A basic demographic measure not adjusted for age structure.

A concave side suggests high mortality or emigration at certain ages. Indicates population loss due to deaths or out-migration.

Population density is the number of people living per unit of area, typically per square kilometer or mile. Measures how concentrated people are in a given space.

Demography is the study of population statistics. The scientific study of human populations and their characteristics.

Replacement-level fertility is the TFR at which a population exactly replaces itself from one generation to the next, typically 2.1. 2.1 accounts for infant mortality and ensures population stability.

The Total Fertility Rate is the average number of children born to a woman over her lifetime. Measures reproductive behavior across a woman's reproductive years.