Population: size, growth, structure and effects on the economy

What you'll learn

This topic examines how population characteristics shape economic development and government policy. You'll understand how birth rates, death rates and migration affect population size, how age distribution creates economic challenges, and why governments intervene to manage demographic change. These concepts appear frequently in Paper 1 and Paper 2, often linked to development, government policy, and labour market questions.

Key terms and definitions

Birth rate — the number of live births per 1,000 people per year in a population

Death rate — the number of deaths per 1,000 people per year in a population

Net migration — the difference between immigration (people entering a country) and emigration (people leaving a country)

Dependency ratio — the ratio of economically inactive people (children aged 0-14 and elderly aged 65+) to the working-age population (aged 15-64), expressed as a percentage

Ageing population — a population structure where the proportion of elderly people (typically 65+) is increasing relative to younger age groups

Population distribution — how people are spread across a geographical area, such as urban versus rural locations

Natural increase — the difference between birth rate and death rate, showing population growth excluding migration

Optimum population — the theoretical population size that maximizes output per head (GDP per capita) given available resources and technology

Core concepts

Population size and growth

Population size changes through three main factors: births, deaths, and net migration. The population growth rate combines natural increase with net migration.

Factors affecting birth rates:

• Income levels (higher incomes often correlate with lower birth rates)
• Cultural and religious attitudes towards family size
• Female education and employment opportunities
• Availability and cost of contraception
• Government population policies (incentives or restrictions)
• Infant mortality rates (where child survival is uncertain, families have more children)

Factors affecting death rates:

• Healthcare quality and accessibility
• Nutrition and food security
• Sanitation and clean water provision
• Disease prevalence
• Living standards and working conditions
• Age structure of the population

Developed countries typically have low birth rates (10-15 per 1,000) and low death rates (8-10 per 1,000), resulting in slow or negative natural population growth. Many European countries now rely on net migration to maintain population size.

Developing countries historically had high birth and death rates. As death rates fall due to improved healthcare while birth rates remain high, rapid population growth occurs. Countries like Nigeria experience annual growth rates exceeding 2.5%, creating pressure on resources, infrastructure and employment.

The demographic transition model

The demographic transition model shows how populations change as countries develop economically:

Stage 1 (High stationary):

• High birth rates and high death rates
• Population remains stable but low
• Few countries remain in this stage

Stage 2 (Early expanding):

• Death rates fall rapidly due to healthcare improvements
• Birth rates remain high
• Rapid population growth
• Examples: Afghanistan, several sub-Saharan African countries

Stage 3 (Late expanding):

• Birth rates begin falling as education improves and urbanization increases
• Death rates continue falling but more slowly
• Population growth slows
• Examples: India, Bangladesh

Stage 4 (Low stationary):

• Low birth rates and low death rates
• Population growth minimal or negative
• Examples: UK, Germany, Japan

Stage 5 (Declining):

• Birth rates fall below death rates
• Natural population decrease
• Examples: Japan, Italy (without migration)

Understanding this model helps explain why population policies differ between countries and why migration flows typically move from Stage 2/3 countries to Stage 4/5 countries.

Population structure and the dependency ratio

Population pyramids graphically represent age-sex distribution. The shape reveals economic challenges:

Expanding pyramid (wide base, narrow top):

• Large proportion of young dependants
• High dependency ratio
• Pressure on education and healthcare for children
• Future employment challenges as children reach working age
• Common in developing countries

Stationary pyramid (relatively even distribution):

• Balanced age structure
• Moderate dependency ratio
• Stable workforce
• Typical of emerging economies

Contracting pyramid (narrow base, wide middle/top):

• Ageing population structure
• Rising proportion of elderly dependants
• Increased healthcare and pension costs
• Labour shortages
• Common in developed countries

The dependency ratio calculation:

Dependency ratio = [(Population aged 0-14 + Population aged 65+) / Population aged 15-64] × 100

A dependency ratio of 60% means 60 dependants for every 100 workers. High ratios strain public finances as fewer workers support more dependants through taxation.

Japan has a dependency ratio exceeding 70%, with over 28% of its population aged 65+. This creates fiscal pressure as pension and healthcare costs rise while the tax base shrinks.

Effects of population change on economic growth

Impact of rapid population growth (developing countries):

Negative effects:

• Resources spread thinly across more people, reducing GDP per capita
• Capital dilution — investment divided among more workers, reducing productivity
• Pressure on infrastructure (schools, hospitals, housing)
• Environmental degradation from overuse of land and resources
• Food insecurity if agricultural production cannot keep pace
• Unemployment and underemployment as job creation lags behind workforce growth

Potential positive effects:

• Large workforce can attract foreign direct investment
• Growing domestic market stimulates demand and business growth
• Innovation increases with larger talent pool
• Economies of scale in production

Impact of ageing populations (developed countries):

Negative effects:

• Higher government spending on pensions and elderly healthcare
• Smaller workforce may reduce total output
• Skills shortages in key sectors
• Higher taxation on working population to fund age-related spending
• Reduced innovation if fewer young workers enter the workforce
• Housing market impacts as elderly downsize

Potential positive effects:

• Older workers have experience and skills
• Reduced unemployment pressure
• Growth in "silver economy" sectors (healthcare, leisure for elderly)
• Incentive for productivity-enhancing technology investment

The UK spends approximately £110 billion annually on state pensions, representing about 5% of GDP. This proportion rises as the population ages, requiring higher National Insurance contributions or increased retirement ages.

Population distribution and density

Population density measures people per square kilometre. High density areas (urban regions) versus low density areas (rural regions) create distinct economic patterns.

Urbanization — the movement of people from rural to urban areas — accelerates in developing countries. Over 55% of the world's population now lives in urban areas.

Economic effects of urbanization:

Advantages:

• Economies of scale in infrastructure provision
• Labour market concentration attracts businesses
• Knowledge spillovers and innovation clusters
• Access to markets and services

Disadvantages:

• Congestion costs (time and pollution)
• Housing shortages driving up prices
• Pressure on urban services
• Informal settlements and poverty in rapidly growing cities
• Rural depopulation reducing agricultural productivity

Mumbai has population density exceeding 20,000 people per km², creating housing costs that consume 30-50% of household income for many workers. Meanwhile, rural Maharashtra experiences labour shortages during harvest seasons as young workers migrate permanently to cities.

Government population policies

Governments intervene in population dynamics to address economic challenges.

Pro-natalist policies (encouraging births):

• Financial incentives: child benefits, tax credits, parental leave
• Childcare subsidies reducing costs of working with children
• Housing support for larger families
• Immigration policies to supplement low birth rates

Singapore offers Baby Bonus payments up to S$10,000 per child plus matched savings contributions. France provides generous family allowances and subsidized childcare. These policies aim to prevent workforce decline and maintain taxpayer numbers.

Anti-natalist policies (reducing births):

• Family planning services and contraception provision
• Education campaigns about family size
• Incentives for smaller families
• Economic penalties for larger families (controversial)

China's former one-child policy (1979-2015) reduced birth rates dramatically but created a rapidly ageing population with gender imbalance. The policy was relaxed to two children (2015) then three (2021) as concerns about workforce decline intensified.

Migration policies: Countries with ageing populations use immigration to supplement workforces. The UK's points-based immigration system prioritizes skilled workers in shortage occupations. Canada and Australia run similar programmes, recognizing that net migration helps maintain tax revenues and economic growth.

However, immigration faces political challenges around cultural integration, wage effects on existing workers, and pressure on housing and public services.

Optimum population theory

Optimum population represents the ideal population size maximizing GDP per capita given available resources and technology. This theoretical concept suggests:

• Underpopulation exists when population is below optimum — adding workers increases output per head as resources are underutilized
• Overpopulation exists when population exceeds optimum — adding workers decreases output per head as resources become strained

In practice, optimum population is difficult to measure because:

• Technology constantly changes resource productivity
• International trade allows countries to exceed resource constraints
• Living standards depend on factors beyond population size
• Different groups define "optimum" differently (economic output versus quality of life)

Australia, with 3 people per km² and abundant natural resources, might be considered underpopulated economically, though immigration remains politically contested. Bangladesh, with 1,265 people per km² and limited resources, faces overpopulation challenges.

Worked examples

Question 1: Explain two reasons why birth rates are higher in developing countries compared to developed countries. [4 marks]

Model answer:

One reason is lower female education and employment in developing countries. When women have limited access to education and formal employment opportunities, they typically have more children as their economic role centers on family care rather than careers. This contrasts with developed countries where educated women participate in the workforce and delay or limit childbearing. [2 marks for developed explanation]

Another reason is higher infant mortality rates in developing countries. Where child survival is uncertain due to poor healthcare and nutrition, families have more children to ensure some survive to adulthood and can support parents in old age. In developed countries, low infant mortality means families need fewer children to achieve desired family sizes. [2 marks for developed explanation]

Question 2: A country has an ageing population. Discuss whether this will benefit or harm its economy. [8 marks]

Model answer:

An ageing population may harm the economy through increased government spending. As the proportion of elderly people rises, the government must spend more on state pensions and elderly healthcare, including expensive treatments for age-related conditions. This means higher taxation on the working population or cuts to other spending areas like education and infrastructure, potentially reducing long-term growth. [3 marks for developed argument with example]

Additionally, an ageing population reduces the size of the workforce. With fewer people of working age, total economic output may fall, and labour shortages may emerge in key sectors. This could reduce international competitiveness and discourage foreign investment, harming economic growth. [3 marks for developed argument]

However, an ageing population can benefit the economy by creating growth in the "silver economy." Sectors serving elderly consumers—such as healthcare, pharmaceuticals, leisure services, and retirement housing—expand, creating employment and business opportunities. Japan's robotics industry, for example, has grown partly to address elderly care needs. [2 marks for counterargument with example]

Overall, most economists view rapid ageing as economically challenging, particularly the fiscal burden of pensions and healthcare, though specific sectors do benefit. [Concluding judgment for full marks]

Question 3: Calculate the dependency ratio for Country X using the following data:

• Population aged 0-14: 8 million
• Population aged 15-64: 20 million
• Population aged 65+: 4 million [2 marks]

Model answer:

Dependency ratio = [(8 million + 4 million) / 20 million] × 100 [1 mark for correct method]

= (12 million / 20 million) × 100 = 60% [1 mark for correct answer]

Common mistakes and how to avoid them

• Confusing birth/death rates with natural increase. Birth rate and death rate are separate measures per 1,000 people. Natural increase is the difference between them. Always specify which you're discussing.

• Ignoring migration when explaining population change. Population size changes through natural increase AND net migration. Many developed countries now have natural decrease but overall population growth due to immigration—don't forget this component.

• Treating all population growth as negative. In developing countries, rapid growth creates challenges. In developed countries facing ageing and workforce decline, moderate population growth through controlled immigration can be economically beneficial. Context matters.

• Misunderstanding dependency ratio. The dependency ratio measures the proportion of dependants to workers, not the absolute numbers. A country can have low absolute numbers of elderly but still a high dependency ratio if its working-age population is also small.

• Oversimplifying ageing population effects. Don't just list negatives. Exam questions often ask to "discuss" or "assess," requiring balanced analysis including positive effects like silver economy growth or productivity incentives.

• Confusing population policies between country types. Pro-natalist policies suit developed countries with ageing populations; anti-natalist policies suit developing countries with rapid growth. Don't recommend the wrong policy for a country's situation.

Exam technique for "Population: size, growth, structure and effects on the economy"

• Command words matter: "Explain" requires you to give reasons with development (aim for 2-3 sentences per point). "Discuss" or "Assess" requires balanced arguments examining both sides with a conclusion. "Calculate" needs the correct formula shown with clear working.

• Use data and examples: When discussing population effects, reference real countries (UK, Japan, Nigeria) or specific data (dependency ratios, percentages, spending figures). This demonstrates application skills worth higher marks.

• Link population to other topics: Population questions often connect to living standards, government spending, labour markets, or development. Make these links explicit—e.g., "ageing populations increase government spending, requiring higher taxation or borrowing, which may crowd out private investment."

• Structure 6-8 mark questions: Use separate paragraphs for each major point. For "discuss" questions, develop 2-3 arguments on one side, then 1-2 counterarguments, followed by a brief judgment stating which side is stronger and why.

Quick revision summary

Population size changes through births, deaths, and net migration. Developing countries typically have high birth rates and young populations, creating pressure on resources and employment. Developed countries have low birth rates and ageing populations, increasing dependency ratios and government spending on pensions and healthcare. The demographic transition model shows how populations evolve as countries develop. Governments use pro-natalist policies to address ageing and anti-natalist policies to slow rapid growth. Population structure significantly impacts economic growth, productivity, government spending, and living standards. Understanding these relationships is essential for analyzing development challenges and government policy choices.