State which outcome depends on the size and timing of the shocks.
A useful AD/AS explanation connects evidence to a determinant, the relevant curve shift and the resulting output-price effects. Then test the assumptions that matter most: the time horizon, spare capacity, import dependence, expectations and simultaneous shocks. A diagram organises a causal argument; it does not estimate the size of a shock from a headline or prove which cause dominated. Distinguish a demand effect today from a supply effect that takes time to develop. A balanced judgement identifies the condition that would change the conclusion, rather than adding a generic list of limitations.
- Mechanism first
- Connect evidence to a determinant and a curve before stating output and price effects.
- Time horizon
- A capital purchase can support spending now and productive capacity later.
- Conditional judgement
- Name the factor that determines the uncertain outcome and the evidence needed to assess it.
Apply the idea
Simultaneous changes
Separate the demand and supply channels, including imported-cost and foreign-demand effects.
Evidence versus model
A dated official account can support a mechanism without identifying its exact size or proving the model explains every observed change.
Worked example: Exports recover while energy costs rise
A report says exports are recovering while imported energy becomes more expensive. New machinery is arriving, but it will take six months to become productive. No sizes are given for the demand or cost changes.
- Stronger exports support an AD increase; more expensive energy supports an adverse AS shift, if each effect is economy-wide and other conditions are held constant.
- Both immediate changes put upward pressure on the price level. Their output effects oppose, so the net output change is uncertain without relative magnitudes.
- The new machinery can improve AS later, but installation, skills and whether it adds usable capacity determine the scale and timing.
- A stronger answer would seek expenditure changes, exposure to imported energy and available capacity. It would not claim the report alone proves a precise growth rate.
Watch out for this
A diagram with two arrows proves the observed percentage change in GDP.
The diagram shows conditional directions. Quantification requires suitable data and a justified model of the shifts and responses.
Check your understanding
Exports rise while energy costs rise, and no relative sizes are given. Under the usual curves, which is best supported?
- Output certainly rises and prices certainly fall.
- Prices rise, while the output effect is uncertain.
- Both curves must remain unchanged.