Externalities and market failure
Explain the gap between private incentives and effects on third parties.
What you will learn
- Identify negative production externalities.
- Relate private and social costs.
Who bears the effect?
An externality is an effect on a third party that is not fully reflected in the market transaction. Pollution from production can impose costs on nearby residents who are neither the producer nor the buyer.
Distinguish production from consumption externalities by identifying the activity causing the effect. Distinguish negative from positive effects by whether third parties experience costs or benefits.
Connect the gap to allocation
With a negative production externality, marginal social cost exceeds marginal private cost. If decisions consider only private costs and benefits, market output can exceed the socially efficient level under the standard competitive model.
A tax, regulation or another policy may address the gap, but evaluation should consider information, enforcement and side effects rather than assuming any intervention is perfectly calibrated.
Worked example
A factory pays its workers and suppliers, but its smoke damages nearby crops without compensation. Classify the externality.
Show the worked solution
- The harm arises from production.
- Farmers are third parties to the factory's sales.
- Their uncompensated loss is an external cost.
Answer A negative production externality
Common mistakes
- A firm's own wage bill is a private cost, not an external cost.
- Identify the affected third party.
What can you explain now?
Why can private production costs understate social costs?
Compare with the explanation
They can exclude costs imposed on third parties
Adding external costs accounts for effects not fully represented in the firm's own payments.
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These lessons teach the topics represented in our current practice sets. They are not a complete course for every paper or option in the qualification.
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