demography midterm

Social demography

The study of the social, economic, cultural, and political causes and consequences of demographic processes.

Mercantilism (17th-18th c)

the more people, the more power, military, and wealth for rulers

cornucopian

Technological progress has no limits and therefore population growth will not cause decline in welfare

Malthusian Trap

For most of human history, real incomes and population size were stagnant or oscillating around a stationary level. cannot rise

Main components of population change

Births, deaths, immigration, and emigration.

Demographic balancing equation

The equation that describes how population size changes over time based on births, deaths, and migration.

Net migration

The difference between immigration and emigration.

Population structure

The composition of a population by characteristics such as age and sex.

Population distribution

The spatial arrangement of people across geographic areas.

Population trends

Long-term patterns in population growth, distribution, and structure.

Global population growth over the last two centuries

increased rapidly due largely to declines in mortality.

Why population growth accelerated

Declines in mortality due to improved medicine, sanitation, and living standards.

Future population growth projections

Global population may reach about 9 billion around 2037 and 10 billion later in the century.

Regions expected to have most population growth

Africa and Asia.

Urbanization historically

In 1800 less than 1% of people lived in cities of 100,000 or more.

Urbanization today

More than half of the global population lives in large cities.

Main drivers of urbanization

Industrialization, trade development, and mechanization of agriculture.

Demographic drivers of political instability

Rapid demographic changes, youth bulges, migration flows, and changing family structures.

Youth bulge

A large proportion of young people in the population that can strain economic and political systems.

Challenges caused by youth bulges

Unemployment, housing shortages, and pressure on education and healthcare systems.

Why education lowers fertility

Education raises opportunity costs of childbearing and increases investment in child quality.

Marriage squeeze

A demographic imbalance where one sex outnumbers the other in marriageable age groups.

Cause of marriage squeeze

Large birth cohorts (e.g., baby boom) creating unequal sex ratios in marriage markets.

Demographic transition theory

A theory explaining the shift from high birth and death rates to low birth and death rates as societies develop.

which stage has the most growth?

More population growth occurs in the early expanding (Stage 2) phase. 3rd is next

Possible stage 5 of demographic transition

Fertility falls below mortality leading to population decline.

Who developed the demographic transition theory

Frank Notestein expanded earlier observations into a general theory in 1945.

Factors causing fertility decline

Declining child mortality, contraception, education, urbanization, and higher opportunity costs of children.

Quality-quantity trade-off

Parents choose fewer children but invest more resources in each child.

Opportunity cost of children

Higher wages and career opportunities make raising children more expensive.

Old-age security hypothesis

Declining fertility occurs when people rely less on children for support in old age.

Demographic data

Data used to measure and analyze population processes.

Why demographic data are important

They help test demographic theories and inform public policy decisions.

Policy uses of demographic data

Governments use population data to plan schools, healthcare, and infrastructure.

Sources of demographic data

Census

A complete enumeration of a whole population at a specific point in time, by law every 10ish years. stock data

Stock data

A stock measures the number of people in a population at a specific moment in time. It is like taking a photograph of the population.

Major issue with censuses

Undercounting of certain populations, like african american

Historical census limitation

Older censuses often underreport female labor force participation.

Age heaping

The tendency for people to report ages ending in certain digits such as 0 or 5.

Vital registration system, stock or flow?

flow data!

Vital registration system/ the statistics it produces

Registro Civil (historically in Europe priests kept them) • Birth • Death • Marriage and divorce • Adoptions • Name changes • Nationalizations

Flow data

A flow measures events that occur over a period of time. It tracks changes in the population.

an example: spanish Population Register

a living registry, mainly spain, Very important source of demographic data. Managed by municipality and used to collect municipal taxes, for electoral participation

What is included in the population register?

Where you live, when you moved there, and where you lived before that. has both stock and flow bc it updates

Capture-recapture method

A statistical technique used to estimate the size of hidden populations.

Basic idea of capture-recapture

The overlap between two samples is used to estimate the total population.

Large overlap=Smaller population

Small overlap=Larger population

Main assumption of capture-recapture

The probability of appearing in one list should be independent of appearing in another.

Interpolation

A method used to estimate population size between two known data points.

Linear interpolation

Assumes population changes at a constant rate between two points, not always applicable since some nations dont experience this

Why interpolation may produce biased estimates

If population growth changes due to unexpected events.

Extrapolation

A method used to estimate future population values based on past trends.

Limitation of extrapolation

It may fail if demographic patterns change significantly.

Demographic measures

Statistics used to compare demographic events across populations.

Why demographic measures are necessary

Absolute numbers cannot be compared across populations of different sizes.

Ratio

indicates the relative magnitude of a numerator and denominator, they are related to each other in some way, but the same person cannot be in both

Example of ratio

Dependency ratio comparing dependent and working-age populations.

Rate, special type of ratio

measure of the frequency with which an event occurs in a defined population during a given length of time. same person is counted in both numerator and denominator.

What is denominator of a rate?

total people/options at risk of the event. if population, MID YEAR POPULATION

Probability

The chance that a demographic event occurs within a defined population at risk.

Lexis diagram

Axes of a Lexis diagram

Time is on the horizontal axis and age is on the vertical axis.

Lifeline in a Lexis diagram

A diagonal line representing an individual's life from birth onward.

Slope of lifelines in a Lexis diagram

45 degrees because individuals age one year for every year of time.

Cohort

a group of people followed simultaneously through time and age (often people born in same year or five-year time span)

Period

refers to a particular point in time (year, five-year time span, decade …)

How to count population size in a Lexis diagram

Draw a vertical line and count lifelines crossing it.

How to count survivors to a specific age

Draw a horizontal line at that age and count lifelines crossing it.

How to follow a cohort in a Lexis diagram

Follow a diagonal line across time and age.

Period measures

Measures where numerator and denominator refer to events occurring in the same time period.

Examples of period measures

Crude death rate, period life expectancy, and total fertility rate.

Cohort measures

Measures that follow the same group of people throughout their life course.

Examples of cohort measures

Cohort fertility rate and cohort life expectancy.

Person-years lived

The total number of years lived by individuals in a population or cohort.

Period person-years

Sum of lifelines within a time interval.

Cohort person-years

Sum of lifelines of a cohort over their lifetime.

Population at risk

The population that could potentially experience a demographic event during a specified time period.

Exposure

The total amount of time individuals in a population are exposed to the risk of experiencing an event.

Person-years of exposure

The sum of the time each individual spends at risk of experiencing an event.

Crude rate

A demographic rate calculated for the entire population without accounting for differences in population structure.

Why crude rates can be misleading

They do not control for differences in age or population composition.

General rate

A rate that restricts the population at risk to those who could realistically experience the event.

Specific rate

A rate calculated for a specific subgroup of the population such as age or sex.

Limitation of crude birth rate

It includes people not at risk of giving birth such as men and children.

General Fertility Rate (GFR)

The number of live births per 1,000 women of reproductive age (typically ages 15–49).

Advantage of general fertility rate

It focuses only on women who are biologically capable of giving birth.

Age-Specific Fertility Rate (ASFR)

The fertility rate for women in a specific age group.

Purpose of ASFR

It shows fertility patterns across different ages.

Total Fertility Rate (TFR)

The average number of children a woman would have over her lifetime if current age-specific fertility rates remain constant.

TFR = sum ASFRx \times n

Meaning of Total Fertility Rate

It estimates completed fertility for a hypothetical woman experiencing current fertility rates.

Replacement fertility

The level of fertility required for a population to replace itself without migration.

Replacement fertility value in developed countries

About 2.1 children per woman.

Crude Death Rate (CDR)

The number of deaths per 1,000 population in a given year.

Why crude death rates may misrepresent mortality risk

Older populations naturally have higher crude death rates.

Age-Specific Death Rate (ASDR)

The death rate for a specific age group.

Infant mortality rate (IMR)

The number of deaths of infants under age 1 per 1,000 live births.

Why infant mortality rate is important

It reflects the overall health conditions of a society.

Natural increase

The difference between births and deaths in a population. r = CBR - CDR

Positive natural increase

When births exceed deaths.