01Model
Build the economic model
Many firms sell differentiated products with relatively low entry barriers. Differentiation gives a downward-sloping demand curve, while entry can erode supernormal profit.
For monopolistic competition, state the relationship between product differentiation and the relevant agents, then identify the ceteris-paribus conditions. The model is a disciplined simplification, not a complete description of reality.
- Define the central variables precisely.
- Identify the agents making decisions.
- State what is held constant and why that matters.
02Evidence
Apply evidence and data
Independent coffee shops compete through location, service, branding and product variety.
Application in monopolistic competition means using scale, direction, timing and source to alter the argument. Explain how the evidence changes the mechanism instead of merely naming the context or copying a figure.
- Check units, dates and whether values are nominal or real.
- Separate correlation from a supported causal inference.
- Identify winners, losers and the appropriate counterfactual.
03Analyse
Develop the mechanism
Successful differentiation shifts firm demand → short-run profit attracts entry → each firm's demand may fall or become more elastic → long-run profit is pressured.
Carry this monopolistic competition chain far enough to answer the question: identify the agent's response, the resulting market or macroeconomic change and why the outcome matters.
- Explain each arrow in the chain.
- Use the diagram or calculation in the written analysis.
- Distinguish short-run adjustment from longer-run response.
04Evaluate
Evaluate assumptions and magnitude
Variety and innovation may compensate consumers for higher cost or excess capacity, so static efficiency is not the only welfare criterion.
Evaluation of monopolistic competition should change confidence in the result. Test elasticity, time lags, scale, incentives, distribution and unintended effects rather than adding a generic “however”.
- Which assumption is most fragile?
- Would a different elasticity reverse or only weaken the result?
- What evidence could change the judgement?
05Judge
Reach an informed judgement
For monopolistic competition, choose the argument with the greatest contextual importance and explain why it outweighs the alternative. State the conditions under which it holds rather than repeating the introduction.
The opportunity cost and distributional effect of product differentiation matter. Political preferences may affect objectives, but the exam judgement must rest on transparent assumptions and evidence rather than ideology.
- Answer the exact command and scope.
- Rank the decisive factors.
- State a condition, timeframe and possible reason to revise the conclusion.
From theory to a testable claim
Many firms sell differentiated products with relatively low entry barriers. Differentiation gives a downward-sloping demand curve, while entry can erode supernormal profit.
Applied taskIndependent coffee shops compete through location, service, branding and product variety.
Causal chain
Successful differentiation shifts firm demand → short-run profit attracts entry → each firm's demand may fall or become more elastic → long-run profit is pressured.
Applied taskRewrite the monopolistic competition chain with one piece of numerical or contextual evidence at the link where it changes the expected magnitude.
Evaluation that does work
Variety and innovation may compensate consumers for higher cost or excess capacity, so static efficiency is not the only welfare criterion.
Applied taskExplain whether this consideration weakens, delays, redistributes or reverses the predicted monopolistic competition outcome.