1.4.6
The Deadweight Welfare Loss of Externalities
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Examples of Externalities
Consumers under and over consume goods and services because they don't take into account the external benefit or cost of their consumption. Firms can under or overproduce goods because they don't account for externalities in their production.

Education
- A good with positive consumption externalities is often called a merit good.
- Education has a positive consumption externality, so it is a merit good.
- In education the MSB>MPB, so it is under consumed in the free market below the socially optimal level.

Petrol cars
- Petrol cars have negative consumption externalities. This means that they are demerit goods.
- Demerit goods are over consumed in the free market. This leads to a deadweight welfare loss to society.

Absence of property rights
- The absence of property rights means that it is not clear who owns what.
- For example, it is not clear who owns the environment or air. This can lead firms to pollute more than is optimal because they do not account for external costs.
- Ronald Coase found that allocating property rights is one way to stop market failures from happening. This is called Coase Theorem.
- The absence of property rights can lead to market failure.

Renewable energy
- Renewable energy has positive production externalities.
- It can replace the use of fossil fuels which can damage the environment - the opportunity cost would be using something negative instead of something neutral.
- Governments have subsidised renewable energy (like wind and solar power) in the US and UK to try to increase production closer to the socially optimal level and deliver a gain in society's welfare.
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Alcohol
- Alcohol has a negative consumption externality.
- Excessive alcohol consumption is linked to crime and antisocial behaviour which the rest of society has to deal with. The consumer doesn't pay the cost that the externality causes leading to the overconsumption of the negative consumption externality.
- The MSB < MPB and this creates a welfare loss unless the government intervenes.

Vaccination
- Vaccination has positive consumption externalities.
- In addition to protecting someone from an illness, vaccination also reduces the risk of that person spreading the illness. As a result, the rest of society is better protected from the illness due to one person's consumption of the vaccine. This is called herd immunity.
1Microeconomics
1.1Competitive Markets: Demand & Suply
1.2Elasticity
1.3Government Intervention
1.4Market Failure
1.4.1Types of Market Failure1.4.2Introduction to Externalities1.4.3Negative Externalities1.4.4Policy for Negative Externalities1.4.5Positive Externalities1.4.6The Deadweight Welfare Loss of Externalities1.4.7Case Study - The Externalities of Education1.4.8Public Goods & the Free-Rider Problem1.4.9Asymmetric Information1.4.10End of Topic Test - Market Failure1.4.11Application Questions - Market Failure
1.5HL: Theory of the Firm & Market Structures
2Macroeconomics
2.1The Level of Overall Economic Activity
2.2Aggregate Demand & Aggregate Supply
2.2.1The Aggregate Demand Curve2.2.2Components of Aggregate Demand2.2.3Shape of the Aggregate Demand Curve2.2.4Shifts in Aggregate Demand2.2.5IB Multiple Choice - Aggregate Demand2.2.6Short & Long-Run Aggregate Supply2.2.7Alternative Models of LRAS2.2.8Equilibrium in the AD-AS Model2.2.9Output Gaps & the AD-AS Model
2.3Macroeconomic Objectives
2.3.1Introduction to Unemployment2.3.2Limitations of Unemployment2.3.3Types of Unemployment2.3.4Causes & Impact of Unemployment2.3.5Defining Inflation2.3.6Measuring Inflation2.3.7Use of Index Numbers2.3.8The Consumer Price Index2.3.9Consequences of Inflation2.3.10Causes of Inflation2.3.11Inflation & Unemployment Tradeoff2.3.12The Short-Run Phillips Curve2.3.13The Long-Run Phillips Curve
2.4Economic Growth, Poverty & Inequality
2.5Fiscal Policy
2.6Monetary Policy
2.7Supply-Side Policies
3The Global Economy
3.1International Trade
3.2Exchange Rates
3.3The Balance of Payments
3.4Economic Integration
3.5Terms of Trade
3.6Economic Development
3.7The Role of Domestic & International Factors
3.8The Role of International Trade
3.9The Role of Foreign Aid
Jump to other topics
1Microeconomics
1.1Competitive Markets: Demand & Suply
1.2Elasticity
1.3Government Intervention
1.4Market Failure
1.4.1Types of Market Failure1.4.2Introduction to Externalities1.4.3Negative Externalities1.4.4Policy for Negative Externalities1.4.5Positive Externalities1.4.6The Deadweight Welfare Loss of Externalities1.4.7Case Study - The Externalities of Education1.4.8Public Goods & the Free-Rider Problem1.4.9Asymmetric Information1.4.10End of Topic Test - Market Failure1.4.11Application Questions - Market Failure
1.5HL: Theory of the Firm & Market Structures
2Macroeconomics
2.1The Level of Overall Economic Activity
2.2Aggregate Demand & Aggregate Supply
2.2.1The Aggregate Demand Curve2.2.2Components of Aggregate Demand2.2.3Shape of the Aggregate Demand Curve2.2.4Shifts in Aggregate Demand2.2.5IB Multiple Choice - Aggregate Demand2.2.6Short & Long-Run Aggregate Supply2.2.7Alternative Models of LRAS2.2.8Equilibrium in the AD-AS Model2.2.9Output Gaps & the AD-AS Model
2.3Macroeconomic Objectives
2.3.1Introduction to Unemployment2.3.2Limitations of Unemployment2.3.3Types of Unemployment2.3.4Causes & Impact of Unemployment2.3.5Defining Inflation2.3.6Measuring Inflation2.3.7Use of Index Numbers2.3.8The Consumer Price Index2.3.9Consequences of Inflation2.3.10Causes of Inflation2.3.11Inflation & Unemployment Tradeoff2.3.12The Short-Run Phillips Curve2.3.13The Long-Run Phillips Curve
2.4Economic Growth, Poverty & Inequality
2.5Fiscal Policy
2.6Monetary Policy
2.7Supply-Side Policies
3The Global Economy
3.1International Trade
3.2Exchange Rates
3.3The Balance of Payments
3.4Economic Integration
3.5Terms of Trade
3.6Economic Development
3.7The Role of Domestic & International Factors
3.8The Role of International Trade
3.9The Role of Foreign Aid
Practice questions on The Deadweight Welfare Loss of Externalities
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