2.1.2
Externalities
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Externalities
Externalities are the effects that producing or consuming goods have on other third parties or society as a whole. Buyers or producers do not consider externalities when making decisions. This can lead to market failure because goods or services can be under or over consumed.

Positive consumption externalities
- This is a 'good' externality created in the consumption of a good.
- The marginal social benefit is the total benefit of consuming a good or service to society. MSB = MPB + Externality.
- If the consumption externality is positive, then the marginal social benefit is more than the marginal private benefit.
- Consumers do not account for the benefit of the externality and this good will be under-consumed.
- E.g. school education is a positive consumption externality because students become more productive for employers.
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Negative consumption externalities
- This is a 'bad' externality created in the consumption of goods/services (e.g cigarettes).
- The marginal social benefit is the total benefit of consuming a good or service to society. It is equal to the marginal private benefit plus the value of the consumption externality.
- If the consumption externality is negative, then the marginal social benefit is less than the marginal private benefit and the good will be overconsumed (vs the socially optimal level).
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Positive production externalities
- These are externalities incurred when producing a good or service.
- Marginal social cost = Marginal private cost + Production externality. MSC is the total cost of producing a good or service to society.
- If the production externality is positive, then the social cost is less than the private cost and the good will be underproduced.

Negative production externalities
- These are externalities created when producing a good or service.
- If the production externality is negative, then the social cost is greater than the private cost and the good will be overproduced (vs the socially optimal level).
- E.g a factory producing noise and air pollution is likely to have a social cost larger than the private cost.
Costs and Benefits to Externalities
Externalities are created through an asymmetry of costs or benefits.
Definition of costs
- Private cost:
- The cost to an individual in the market.
- External cost:
- A cost put on a third party due to a negative externality.
- Social cost:
- The cost to society due to a negative externality.
- Social cost = private cost + external cost.
Definition of benefits
- Private benefit:
- The benefit to an individual in the market.
- External benefit:
- The benefit a third party receives due to a positive externality.
- Social benefit:
- The benefit to society due to a positive externality.
- Social benefit = private benefit + external benefit.
1Introduction to Markets
1.1Nature of Economics
1.1.1Economics as a Social Science1.1.2Positive & Normative Economic Statements1.1.3The Economic Problem1.1.4Resources1.1.5Production Possibility Frontiers1.1.6Specialisation & Division of Labour1.1.7Types of Economies1.1.8End of Topic Test - Nature of Economics1.1.9Application Questions - Nature of Economics
1.2How Markets Work
1.2.1Rational Decision Making1.2.2Demand1.2.3Elasticities of Demand1.2.4Elasticities of Demand 21.2.5Elasticity & Revenue1.2.6Supply1.2.7Elasticity of Supply1.2.8Price Determination1.2.9Price Mechanism1.2.10Consumer & Producer Surplus1.2.11Indirect Taxes & Subsidies1.2.12A-A* (AO3/4) - Taxing Prices or Quantities?1.2.13Alternative View of Consumer Behaviour1.2.14End of Topic Test - Markets1.2.15A-A* (AO3/4) - Markets
2Market Failure
2.1Market Failure
2.2Government Intervention
2.2.1Government Intervention in Markets2.2.2Subsidies & Price Controls2.2.3Pollution Permits & Regulation2.2.4A-A* (AO3/4) - European Emissions Trading2.2.5State Provision & Information Provision2.2.6Government Failure2.2.7End of Topic Test - Government Intervention2.2.8A-A* (AO3/4) - Government Intervention
3The UK Macroeconomy
3.1Measures of Economic Performance
3.1.1Measuring Economic Growth3.1.2National Income Data3.1.3Inflation3.1.4Causes of Inflation3.1.5Consequences of Inflation3.1.6Employment & Unemployment3.1.7Causes & Impact of Unemployment3.1.8A-A* (AO3/4) - Hysteresis3.1.9Balance of Payments3.1.10Current Account Deficit & Imbalances3.1.11End of Topic Test - Economic Performance3.1.12Application Questions Macroeconomy
3.2Aggregate Demand
3.3Aggregate Supply
3.4National Income
4The UK Economy - Policies
4.1Macroeconomic Objectives & Policies
4.1.1Possible Objectives4.1.2Demand-Side Policies - Monetary4.1.3Demand-Side Policies - Monetary 24.1.4A-A* (AO3/4) - The Future of Interest Rates4.1.5Demand-Side Policies - Fiscal4.1.6Demand-Side Policies in 2007-084.1.7Strengths & Weaknesses of Demand Side4.1.8Supply-Side Policies4.1.9Supply-Side Policies 24.1.10Conflicts Between Objectives4.1.11A-A* (AO3/4) - Conflicting Incentives4.1.12Phillips Curve4.1.13End of Topic Topic - Policies & Objectives4.1.14Application Questions - UK Policies
5Business Behaviour
5.1Business Growth
5.2Business Objectives
6Market Structures
6.1Market Structures
6.1.1Efficiency6.1.2Perfect Competition6.1.3Perfect Competition 26.1.4Monopolistic Competition6.1.5Oligopolies6.1.6The Prisoner's Dilemma6.1.7Collusion in Oligopolistic Markets6.1.8A-A* (AO3/4) - Which Factors Affect Collusion?6.1.9Monopolies6.1.10Price Discrimination6.1.11Monopsony6.1.12A-A* (AO3/4) - Models in Economics6.1.13Contestability6.1.14Benefits of Contestability6.1.15End of Topic Test - Market Structures6.1.16Application Questions - Market Structures6.1.17A-A* (AO3/4) - Cereal Collusion
6.2Labour Market
6.2.1Demand for Labour6.2.2Supply of Labour6.2.3Labour Market Imperfections6.2.4A-A* (AO3/4) - Labour Productivity & Unemployment6.2.5A-A* (AO3/4) - What Level of Unionisation is Good?6.2.6Wage Determination6.2.7Elasticity of Labour Supply & Demand6.2.8Intervention in Setting Wages6.2.9End of Topic Test - Labour Market6.2.10A-A* (AO3/4) - Labour Markets
6.3Government Intervention
6.3.1Reasons for Government Intervention6.3.2Government Promotion of Competition6.3.3Usefulness of Competition Policy & Examples6.3.4A-A* (AO3/4) - Modern Competition Policy6.3.5Privatisation6.3.6Government Regulation6.3.7A-A* (AO3/4) - Nationalisation vs Privatisation6.3.8Government Protection of Suppliers and Employees6.3.9Impact of Government Intervention6.3.10End of Topic Test - Government Intervention6.3.11Application Questions - Government Intervention
7A Global Perspective
7.1International Economics - Globalisation & Trade
7.2International Economics - Currency
7.2.1Merged Currency7.2.2Restrictions on Free Trade7.2.3Arguments for Protectionism7.2.4Arguments Against Protectionism7.2.5Balance of Payments7.2.6Balance of Payments 27.2.7Floating Exchange Rates7.2.8Fixed Exchange Rate7.2.9International Competitiveness7.2.10End of Topic Test - International Economy7.2.11Application Questions - International Economics
8Finance & Inequality
8.1Poverty & Inequality
8.2Emerging & Developing Economies
8.2.1Measures of Development8.2.2Factors Influencing Growth & Development8.2.3Barriers to Development8.2.4Barriers to Development 28.2.5A-A* (AO3/4) - The Bottom Billion8.2.6Development Strategies8.2.7Interventionist Strategies8.2.8Aid8.2.9International Institutions8.2.10International Institutions 28.2.11End of Topic Test - Emerging & Developing8.2.12Application Questions - Developing Countries
8.3The Financial Sector
8.4Role of the State in the Macroeconomy
9Examples of Global Policy
9.1International Policies
Jump to other topics
1Introduction to Markets
1.1Nature of Economics
1.1.1Economics as a Social Science1.1.2Positive & Normative Economic Statements1.1.3The Economic Problem1.1.4Resources1.1.5Production Possibility Frontiers1.1.6Specialisation & Division of Labour1.1.7Types of Economies1.1.8End of Topic Test - Nature of Economics1.1.9Application Questions - Nature of Economics
1.2How Markets Work
1.2.1Rational Decision Making1.2.2Demand1.2.3Elasticities of Demand1.2.4Elasticities of Demand 21.2.5Elasticity & Revenue1.2.6Supply1.2.7Elasticity of Supply1.2.8Price Determination1.2.9Price Mechanism1.2.10Consumer & Producer Surplus1.2.11Indirect Taxes & Subsidies1.2.12A-A* (AO3/4) - Taxing Prices or Quantities?1.2.13Alternative View of Consumer Behaviour1.2.14End of Topic Test - Markets1.2.15A-A* (AO3/4) - Markets
2Market Failure
2.1Market Failure
2.2Government Intervention
2.2.1Government Intervention in Markets2.2.2Subsidies & Price Controls2.2.3Pollution Permits & Regulation2.2.4A-A* (AO3/4) - European Emissions Trading2.2.5State Provision & Information Provision2.2.6Government Failure2.2.7End of Topic Test - Government Intervention2.2.8A-A* (AO3/4) - Government Intervention
3The UK Macroeconomy
3.1Measures of Economic Performance
3.1.1Measuring Economic Growth3.1.2National Income Data3.1.3Inflation3.1.4Causes of Inflation3.1.5Consequences of Inflation3.1.6Employment & Unemployment3.1.7Causes & Impact of Unemployment3.1.8A-A* (AO3/4) - Hysteresis3.1.9Balance of Payments3.1.10Current Account Deficit & Imbalances3.1.11End of Topic Test - Economic Performance3.1.12Application Questions Macroeconomy
3.2Aggregate Demand
3.3Aggregate Supply
3.4National Income
4The UK Economy - Policies
4.1Macroeconomic Objectives & Policies
4.1.1Possible Objectives4.1.2Demand-Side Policies - Monetary4.1.3Demand-Side Policies - Monetary 24.1.4A-A* (AO3/4) - The Future of Interest Rates4.1.5Demand-Side Policies - Fiscal4.1.6Demand-Side Policies in 2007-084.1.7Strengths & Weaknesses of Demand Side4.1.8Supply-Side Policies4.1.9Supply-Side Policies 24.1.10Conflicts Between Objectives4.1.11A-A* (AO3/4) - Conflicting Incentives4.1.12Phillips Curve4.1.13End of Topic Topic - Policies & Objectives4.1.14Application Questions - UK Policies
5Business Behaviour
5.1Business Growth
5.2Business Objectives
6Market Structures
6.1Market Structures
6.1.1Efficiency6.1.2Perfect Competition6.1.3Perfect Competition 26.1.4Monopolistic Competition6.1.5Oligopolies6.1.6The Prisoner's Dilemma6.1.7Collusion in Oligopolistic Markets6.1.8A-A* (AO3/4) - Which Factors Affect Collusion?6.1.9Monopolies6.1.10Price Discrimination6.1.11Monopsony6.1.12A-A* (AO3/4) - Models in Economics6.1.13Contestability6.1.14Benefits of Contestability6.1.15End of Topic Test - Market Structures6.1.16Application Questions - Market Structures6.1.17A-A* (AO3/4) - Cereal Collusion
6.2Labour Market
6.2.1Demand for Labour6.2.2Supply of Labour6.2.3Labour Market Imperfections6.2.4A-A* (AO3/4) - Labour Productivity & Unemployment6.2.5A-A* (AO3/4) - What Level of Unionisation is Good?6.2.6Wage Determination6.2.7Elasticity of Labour Supply & Demand6.2.8Intervention in Setting Wages6.2.9End of Topic Test - Labour Market6.2.10A-A* (AO3/4) - Labour Markets
6.3Government Intervention
6.3.1Reasons for Government Intervention6.3.2Government Promotion of Competition6.3.3Usefulness of Competition Policy & Examples6.3.4A-A* (AO3/4) - Modern Competition Policy6.3.5Privatisation6.3.6Government Regulation6.3.7A-A* (AO3/4) - Nationalisation vs Privatisation6.3.8Government Protection of Suppliers and Employees6.3.9Impact of Government Intervention6.3.10End of Topic Test - Government Intervention6.3.11Application Questions - Government Intervention
7A Global Perspective
7.1International Economics - Globalisation & Trade
7.2International Economics - Currency
7.2.1Merged Currency7.2.2Restrictions on Free Trade7.2.3Arguments for Protectionism7.2.4Arguments Against Protectionism7.2.5Balance of Payments7.2.6Balance of Payments 27.2.7Floating Exchange Rates7.2.8Fixed Exchange Rate7.2.9International Competitiveness7.2.10End of Topic Test - International Economy7.2.11Application Questions - International Economics
8Finance & Inequality
8.1Poverty & Inequality
8.2Emerging & Developing Economies
8.2.1Measures of Development8.2.2Factors Influencing Growth & Development8.2.3Barriers to Development8.2.4Barriers to Development 28.2.5A-A* (AO3/4) - The Bottom Billion8.2.6Development Strategies8.2.7Interventionist Strategies8.2.8Aid8.2.9International Institutions8.2.10International Institutions 28.2.11End of Topic Test - Emerging & Developing8.2.12Application Questions - Developing Countries
8.3The Financial Sector
8.4Role of the State in the Macroeconomy
9Examples of Global Policy
9.1International Policies
Practice questions on Externalities
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1What does this externality diagram show?Multiple choice
- 2What does this externality diagram show?Multiple choice
- 3What does this externality diagram show?Multiple choice
- 4
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