What is it?
Graph It
Fixing the Market
Real World Examples
100

Who receives the benefit in a positive production externality?

(Unrelated) Third parties

100

Label the socially optimal point.

Market equilibrium for MSC (lower line)

100

What policy is usually used to encourage goods with positive externalities?

Subsidies

100

A company plants trees around its facility. How is this a positive externality?

It filters air and makes the surroundings cleaner, at no cost to nearby third parties.

200

How does social marginal cost (MSC) compare to private marginal cost (MPC) when production benefits third parties?

MSC < MPC

200

Show the deadweight loss area. Label Qmarket, Qsocial, MPC, and MSC.

Triangle between Qmarket and Qsocial and Pmarket

200

Why does the government intervene instead of leaving it to the market?

Because the market underproduces the good

200

Why does a firm’s research and development benefit others?

Knowledge leaks or is copied, which lowers other firm's innovation costs.

300
Why does underproduction occur?

Underproduction happens because firms ignore benefits to others, so output stays below the socially optimal level.

300

Label the external benefit.

External benefit= Positive externality. Between MPC & MSC.

300

Name one real-world good that is subsidized because of positive externalities.

Education, vaccines, green energy, public transport, job training, etc

300

Raising employee salaries improves company morale and creates more productive workers. Does this create a production externality?

No, because the benefits are private and limited to the firm the employees work in. 

400

What 2 things happen over time if a positive production externality isn’t supported by the government?

Production stays too low, and society keeps missing out on the extra benefits that the activity could provide.

400

If each extra unit reduces society’s costs by $20 and 50 extra units are socially optimal, calculate the total unaccounted savings.

Hint: How much does one unit save? Total?

$1,000 (50 × $20)

400

Name one government policy besides subsidies that could increase production of goods with positive externalities.

Tax breaks, grants, regulations/legislations requiring production.

400

Compare a tax break vs. a direct grant for encouraging production.

Tax breaks reduce effective costs indirectly while grants provide direct funds

500

A factory installs filters that reduce neighborhood pollution. Which curve shifts in the graph of social vs private cost?

Social marginal cost curve shifts downward relative to private marginal cost.

500

A factory’s production reduces costs for others, without receiving extra payment. The government creates a per-unit subsidy to reward the firm for these unpriced benefits. Explain how this would affect the graph.

MPC shifts downward to overlap MSC: new Qmarket = Qsocial.

500

What makes it difficult for governments to set the “right” subsidy for goods with positive production externalities?

They can’t easily measure how large the spillover is, so they may end up giving too much or too little support (over- or under-subsidizing). 

500

An environmental lab creates a system to clean its wastewater before it enters the local river, to reduce disposal costs. Over time, residents downstream notice that the water is slightly clearer and requires less filtering before use. Is this significant enough to justify government intervention? Why or why not?

This is a partial positive production externality. The lab captures most of the benefits, so its production will be maintained even without intervention. Downstream residents gain only minor advantages, so government intervention isn’t necessary.