01Model
Build the economic model
Concentration measures the share held by leading firms, but competitive pressure also depends on entry barriers, sunk costs, buyer power, innovation and market definition.
For market concentration and barriers to entry, state the relationship between concentration ratio 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
Four grocery firms hold most national sales, while local and online specialists enter particular segments.
Application in market concentration and barriers to entry 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
Barrier or concentration changes → threat of entry and strategic conduct change → prices, quality, innovation and efficiency may change.
Carry this market concentration and barriers to entry 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
A concentration ratio can mislead when the market is defined too broadly or narrowly and does not directly measure collusion or contestability.
Evaluation of market concentration and barriers to entry 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 market concentration and barriers to entry, 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 concentration ratio 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
Concentration measures the share held by leading firms, but competitive pressure also depends on entry barriers, sunk costs, buyer power, innovation and market definition.
Applied taskFour grocery firms hold most national sales, while local and online specialists enter particular segments.
Causal chain
Barrier or concentration changes → threat of entry and strategic conduct change → prices, quality, innovation and efficiency may change.
Applied taskRewrite the market concentration and barriers to entry chain with one piece of numerical or contextual evidence at the link where it changes the expected magnitude.
Evaluation that does work
A concentration ratio can mislead when the market is defined too broadly or narrowly and does not directly measure collusion or contestability.
Applied taskExplain whether this consideration weakens, delays, redistributes or reverses the predicted market concentration and barriers to entry outcome.