Effects of Changing Population Sizes (Cambridge (CIE) IGCSE Economics)

Revision Note

Steve Vorster

Written by: Steve Vorster

Reviewed by: Jenna Quinn

The Optimum Population

  • Overpopulation occurs when there are more people in a country/region than can be supported by its resources and technology and leads to

    • Higher levels of pollution

    • Higher crime rates

    • Higher unemployment or underemployment

    • Higher levels of food and water shortages 

    • Higher pressure on services such as hospitals and schools 

  • Underpopulation occurs when there are more resources available than the population can use effectively and may lead to

    • Fewer people paying tax which can lead to higher taxes

    • Underused resources, which can lead to wastage

    • A shortage of workers

    • Lower levels of exports and production which affects the wealth of an area

    • Fewer customers for goods and services 

  • Optimum population occurs when there is a balance between the number of people and the resources/technology available  
     

A graph showing GDP per capita vs. total population, with a peak labeled "Optimum Population" and declining sides labeled "Under Population" and "Over Population."
Optimum Theory of Population
  • The optimum population results in the highest standard of living

    • There are not so many people or so few resources that the standard of living falls

    • There are enough people to develop the resources of the country 

Examiner Tips and Tricks

It is important to remember that over-population does not just mean there are a lot of people and under-population that there are few people. The terms refer to the balance between population and resources. There may be many people in a country, but it is only over-populated when there are too few resources to support that population.

Population Distribution

  • The characteristics of a population (the distribution of age, sex, ethnicity, religion etc), is known as the population structure  

  • The population structure is the result of changes in:

    • the birth rate

    • the death rate

    • net migration

  • The two main characteristics of age and sex can be shown on a population pyramid

Population pyramids

  • Population pyramids are used to display the gender and age structure of a given population

    • They illustrate the distribution of population across age groups and between male/female 

  • Population pyramids can be used to identify the following groups:

    • Young dependents 

    • Old dependents e.g number of retired people

    • Economically active (working population or labour force)

    • Dependency ratio 

Example 1 - Niger as a Less Economically Developed Country (LEDC)

Population pyramid of Niger in 2010. Blue bars represent male population and red bars represent female population across different age groups from 0 to 100.
Population Pyramid - Niger
  • LEDCs like Niger have a concave pyramid shape which indicates

    • High birth rate

    • Low life expectancy

    • High death rate but starting to decrease (people dying through every age group)

    • High infant mortality rate (significant decrease between 0-5)

    • Young dependent population dominates the distribution 

Example 2 - USA as a More Economically Developed Country (MEDC) 

Population Pyramid - USA 
Population Pyramid - USA 
  • This population pyramid indicates:

    • Decreasing birth rate  - there is a smaller population reading down from age 29

    • Increasing life expectancy - indicated by the relatively straight sides reaching the age of 70, followed by a good proportion of people living much longer

    • Decreasing death rate - indicated by the relatively straight sides reaching the age of 70

    • Low infant mortality - hardly any change between 0-9 years

    • Larger working age population - 15 to 69 represents a large proportion of the population 

Example 3 - Japan as a More Economically Developed Country (MEDC) 

Population Pyramid - Japan 
Population Pyramid - Japan 
  • This population pyramid indicates

    • Decreasing birth rate - indicated by decreasing population levels from age 29

    • Increasing life expectancy - indicated by the relatively straight sides reaching the age of 74, followed by a good proportion of people living much longer

    • Death rate is higher than the birth rate due to the ageing population

    • Low infant mortality

    • Ageing population - older dependent population with large proportion of the population older than 40 

Effects of Population Changes

  • Population changes can have major impacts within the economy resulting in changes to consumption, production, lifestyle, standards of living and government policies (fiscal, monetary and supply-side) 

  • Typical changes that occur are

    • Progressively ageing populations as economies develop

    • Falling birth rates as economies develop

    • Swings in net migration as influenced by war, famine, natural disasters and government policy 

Ageing populations

  • Many developed economies are experiencing ageing populations and an increase in the older dependent population

  • The implications of this include

    • Increased pension payments by governments

    • Increased need for care homes (public and private)

    • Increased pressure on the healthcare service and social care results in higher government spending

    • It also results in a smaller labour force and often Governments collect less tax

    • Firms suffer worker shortages

    • Labour shortages result in increased wage costs for firms  

Falling birth rates

  • Falling birth rates have the following impact on an economy

    • School closures due to fewer children

    • Future labour shortages 

    • Governments typically put in place incentives that encourage families to have more children

    • Governments may change the migration laws to encourage immigration so that labour shortages are prevented

      • Excessive immigration can change the nature and culture of different regions within a country 

Migration

  • In some countries migration can lead to an imbalance in the population structure e.g. the UAE has significantly more males than females 

  • Rapid population growth caused by migration can lead to

    • Increased pressure on services such as healthcare and schools resulting in increased costs for government

    • A shortage of housing which generates social issues in society

    • Increased traffic congestion which is a negative externality

    • Increased water and air pollution which are negative externalities

    • Food shortages

Last updated:

You've read 0 of your 5 free revision notes this week

Sign up now. It’s free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Steve Vorster

Author: Steve Vorster

Expertise: Economics & Business Subject Lead

Steve has taught A Level, GCSE, IGCSE Business and Economics - as well as IBDP Economics and Business Management. He is an IBDP Examiner and IGCSE textbook author. His students regularly achieve 90-100% in their final exams. Steve has been the Assistant Head of Sixth Form for a school in Devon, and Head of Economics at the world's largest International school in Singapore. He loves to create resources which speed up student learning and are easily accessible by all.

Jenna Quinn

Author: Jenna Quinn

Expertise: Head of New Subjects

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.