Edexcel Economics
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Chain of reasoning

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1. What a chain of reasoning is

A chain of reasoning is a series of linked steps where each one causes the next, running from a starting point to the answer the question wants. It is what the exam board is looking for in analysis: not just naming an effect, but showing how you get there.

Trigger→ soLink 1→ soLink 2→ soLink 3→ soEffect on the question
Weak: a statementEconomies of scale lower costs.
Strong: a chainBuying materials in bulk earns a discount, so the cost per unit falls, so long-run average cost falls. The firm can then cut price and still make the same profit per unit, so it becomes more competitive and its demand rises.

Aim for at least three linked steps in each analysis paragraph. If you can replace "so" between two of your steps with "and also", you have a list, not a chain.

The question's command term decides how far the chain must go. Explain, examine and analyse want a chain that ends at an effect. Evaluate, assess and discuss want chains on both sides, then a weighing up. See the command words page.

2. Building a chain step by step

Use this every time. Each step answers a short question.

  1. Start with the trigger. What changes, or what is the action in the question? A cost rise, a merger, a tax, a fall in demand.
  2. Ask "so what happens to...?" Move to the first direct effect, in economics terms (costs, revenue, price, output, demand, wages).
  3. Keep asking "and so?" Link the effect to the next variable. Stop when you reach something the question cares about: profit, efficiency, consumers, workers, the government.
  4. Anchor it. Use the case study. Pull a figure, a firm or a fact from the extract into the chain at the step where it fits (application).
  5. Say the direction. Rises or falls, more or less. Vague words like "affects" or "impacts" lose marks.
  6. Check the last link answers the question. If the question asks about consumers, your last link must be about consumers.

Useful linking words

which means, so, therefore, this leads to, as a result, which causes, this reduces / increases, meaning that, in turn, because of this.

3. Worked example: a Theme 3 chain

Question: Analyse how a fall in demand might affect a firm's profits. (spec 3.3)

Demand falls→ soAR curve shifts left→ soPrice and MR fall at every output→ soProfit-max output falls (MC = MR)→ soAR is now closer to AC→ soSupernormal profit shrinks, or becomes a loss

To make this an 8-mark answer, tie it to the extract (say, the firm's actual sales fall from X to Y) and draw the shifted AR and MR curves. To make it a 25-mark answer, add a chain on the other side, then evaluate: the size of the fall in profit depends on how much demand falls, how much of the cost is fixed, and whether the fall is short-run or permanent. If AR stays above AVC the firm keeps producing in the short run.

See the interactive profit diagram in 3.2 and 3.3: move the demand slider and watch the chain happen.

4. Common errors that lose marks
Jumping"Minimum wage rises, so unemployment rises." Missing links: labour costs rise, marginal cost rises, profit-max output falls, less labour demanded.
ListingThree separate effects with no link between them. Each effect should come from the one before.
Repeating the question"Costs rise, so costs go up." Nothing new is added by the second half.
Vague direction"This affects profit." Say whether profit rises or falls, and why.
No contextA perfect chain with no reference to the case study caps the application mark.
Wrong end pointThe chain finishes at a different variable from the one the question asks about.

Spot the error

5. Building this into a 25-mark essay

The chain is the engine of each analysis paragraph. Paragraph plan for a 25-mark essay:

  1. Definitions
  2. Analysis: one chain (micro or macro effects)
  3. Evaluation of that chain (natural evaluation, not a bolt-on)
  4. Analysis: a second chain (the opposite of paragraph 2)
  5. Evaluation of that chain
  6. Judgement that weighs the two

Evaluate a chain by testing one link in it: "this might not happen because there is no spare capacity", "the effect depends on the size of the elasticity", "short run versus long run". Weak links are the easiest places to challenge.

Resources

Practice: put the chain in order

Each button is one link. Click them in the order the reasoning runs. The last link should answer the question above each exercise. Wrong clicks do nothing, so keep trying.

Exercise 1: economies of scale

Question: Analyse how economies of scale might affect a firm's competitiveness. (6)

Exercise 2: falling demand

Question: Analyse how a fall in demand might affect a firm's profits. (6)

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