Reasons for government intervention in markets
Reasons for government intervention in markets: build the core model, apply it to evidence and qualify conclusions where outcomes depend on context.
9708 section 3.1; AS Level. Checked against Cambridge's 2026–2028 Version 2 (latest version published December 2025) and 2029 Version 1 (published September 2026). Cambridge states that neither version has significant changes affecting teaching. Always follow the syllabus for the candidate's examination year.
Before you begin
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What is one defining property of a public good?
What you will learn
- Explain non-provision of public goods
- Explain under-consumption of merit and over-consumption of demerit goods
- Analyse reasons to control market prices
Core model and terms
Governments may provide or fund public goods when non-excludability and non-rivalry make it difficult for private sellers to charge users and capture the full benefit. Merit goods may be under-consumed and demerit goods over-consumed when information is incomplete or private incentives differ from social effects.
Apply and evaluate
Price intervention may aim to protect buyers or sellers, but a control changes the market outcome only when it binds. Before evaluating a policy, state the problem, who is affected and what evidence would show that intervention improves the outcome.
Pause and explain
Which statement best applies reasons for government intervention in markets?
Worked example
A flood-warning service benefits nearby households, but no firm can reliably charge every person who uses the warning. Explain a reason for public provision.
Show the worked solution
- The warning is difficult to withhold from non-payers
- One household’s warning does not substantially reduce another’s protection
- A private seller may be unable to collect payment from every beneficiary
Answer The warning is difficult to withhold from non-payers → One household’s warning does not substantially reduce another’s protection → A private seller may be unable to collect payment from every beneficiary
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
A flood-warning service benefits nearby households, but no firm can reliably charge every person who uses the warning. Explain a reason for public provision.
Give me a hint
Check whether users can be excluded and whether one user reduces another’s benefit.
Compare my reasoning
- The warning is difficult to withhold from non-payers
- One household’s warning does not substantially reduce another’s protection
- A private seller may be unable to collect payment from every beneficiary
The warning is difficult to withhold from non-payers One household’s warning does not substantially reduce another’s protection A private seller may be unable to collect payment from every beneficiary
Look for these in your work
- The warning is difficult to withhold from non-payers
- One household’s warning does not substantially reduce another’s protection
- A private seller may be unable to collect payment from every beneficiary
Why may a vaccination be under-consumed when households consider only their private benefit?
Give me a hint
Separate the recipient’s benefit from protection received by others.
Compare my reasoning
- The household considers its own protection
- Vaccination can also reduce transmission to others
- The social benefit may exceed the private benefit
The household considers its own protection Vaccination can also reduce transmission to others The social benefit may exceed the private benefit
Look for these in your work
- The household considers its own protection
- Vaccination can also reduce transmission to others
- The social benefit may exceed the private benefit
A legal minimum price is announced above the market equilibrium. State the likely market imbalance and one condition.
Give me a hint
Compare the control with equilibrium before predicting its effect.
Compare my reasoning
- The floor is above equilibrium
- Quantity supplied tends to exceed quantity demanded
- A surplus can arise if the control is enforced
The floor is above equilibrium Quantity supplied tends to exceed quantity demanded A surplus can arise if the control is enforced
Look for these in your work
- The floor is above equilibrium
- Quantity supplied tends to exceed quantity demanded
- A surplus can arise if the control is enforced
A government caps rents below equilibrium. Explain one intended benefit and one risk for tenants over time.
Give me a hint
Consider the immediate payment and landlords’ future incentives.
Compare my reasoning
- The cap can lower rent for covered tenants
- Returns to supplying or maintaining rental homes may fall
- Availability or quality may weaken unless other conditions offset this
The cap can lower rent for covered tenants Returns to supplying or maintaining rental homes may fall Availability or quality may weaken unless other conditions offset this
Look for these in your work
- The cap can lower rent for covered tenants
- Returns to supplying or maintaining rental homes may fall
- Availability or quality may weaken unless other conditions offset this
Common mistakes
- Assuming every good supplied by government is a public good, or that a price control works even when it does not bind.
What can you explain now?
What is one defining property of a public good?
Compare with the explanation
It is non-excludable and non-rival in consumption
Those properties can make charging each beneficiary difficult.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Before moving on, explain the central idea in reasons for government intervention in markets and state one condition that could change its effect.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.