What is the difference between SRAS and LRAS?

Short-run aggregate supply (SRAS) shows the total output firms are willing to supply at different price levels, given fixed input costs. Long-run aggregate supply (LRAS) represents the economy's maximum productive capacity at full employment. SRAS can shift due to input cost changes; LRAS shifts when the productive capacity of the economy changes (e.g. through investment, education, or technological progress).

How do supply-side policies shift LRAS?

Supply-side policies increase the economy's productive potential. Education and training raise human capital and labour productivity. Deregulation increases competition and efficiency. Lower corporation tax incentivises investment in capital. Infrastructure spending reduces transport costs. All these increase potential output, shifting LRAS rightward and enabling non-inflationary growth.

Edexcel IAL Aggregate Supply Model Answers | Economics

These model answers demonstrate how to structure responses for Edexcel International A-Level (IAL) Economics and Business exams. Each answer includes a mark scheme breakdown, PEEL structure (where applicable), annotated paragraphs, and examiner commentary explaining what earns marks at each band.

8 marks

Unit 2 · 2.3.3 Aggregate Supply · Analysis

Analyse: the impact of supply-side policies on long-run aggregate supply (LRAS).

Mark Scheme Breakdown

1–2 marksKnowledge: definition of supply-side policies and/or LRAS

3–4 marksApplication: specific examples of supply-side policies (education, deregulation, tax reform)

5–8 marksAnalysis: developed chain of reasoning from policy → productivity → LRAS shift → non-inflationary growth

PEEL Structure

Point

Supply-side policies increase the productive capacity of the economy, shifting LRAS rightward.

Evidence

E.g. government investment in education and training increases human capital; deregulation reduces barriers to entry.

Explain

Higher productivity means more output can be produced at every price level. LRAS shifts right, enabling non-inflationary growth.

Link

This raises the trend rate of growth and reduces structural unemployment, though benefits take years to materialise.

KKnowledge

AApplication

AnAnalysis chain

DDiagram ref.

Model Answer

Para 1

Supply-side policies are government measures designed to increase the productive potential of the economy by improving the quality and quantity of factors of production. K Long-run aggregate supply (LRAS) represents the economy's maximum output at full employment of resources. K

Para 2

Interventionist supply-side policies include government investment in education and training, which raises human capital. A A more skilled workforce is more productive — each worker produces more output per hour — which increases the economy's productive capacity. An Similarly, investment in infrastructure (e.g. transport networks) reduces firms' costs and improves efficiency, further expanding potential output. An On a diagram, LRAS shifts rightward from LRAS₁ to LRAS₂, enabling the economy to produce more at every price level. D

Para 3

Market-based supply-side policies such as deregulation and reducing corporation tax work by increasing incentives and competition. A Deregulation removes barriers to entry, increasing competition and driving firms to innovate and cut costs. Lower corporation tax raises post-tax profits, incentivising greater investment in capital equipment and technology. An The resulting rightward shift of LRAS enables non-inflationary economic growth — real GDP rises without upward pressure on the price level — and can reduce structural unemployment by addressing skills gaps and labour market rigidities. An However, these benefits are typically long-term, taking years to materialise, and may involve short-term costs such as government spending on education or transition periods after deregulation. An

Examiner Commentary

This answer demonstrates the developed chain of reasoning examiners reward: policy → productivity/capacity increase → LRAS shifts right → non-inflationary growth + lower structural unemployment. The distinction between interventionist and market-based policies shows breadth. The qualification about time lags elevates the analysis beyond assertion. A correctly labelled LRAS diagram showing the shift would earn diagram credit.

Likely Score7–8 / 8

4 marks

Unit 2 · 2.3.3 Aggregate Supply · Knowledge & Application

Explain: what might cause the short-run aggregate supply (SRAS) curve to shift to the left.

Mark Scheme Breakdown

1–2 marksKnowledge: SRAS and cost-push factors

3–4 marksApplication: named examples of cost increases causing leftward shift

KKnowledge

AApplication

Model Answer

The short-run aggregate supply (SRAS) curve shows the total output firms are willing to supply when some costs (e.g. wages) are fixed. K SRAS shifts left when production costs rise across the economy — at every price level, firms supply less because it is less profitable. K

For example, a sharp rise in oil prices increases energy and transport costs for firms across all sectors, reducing SRAS. A Similarly, a weaker exchange rate increases the cost of imported raw materials, or a rise in the national minimum wage increases labour costs. A In each case, higher costs shift SRAS left, causing cost-push inflation and potentially stagflation.

Examiner Commentary

Clear definition followed by three concrete examples (oil prices, exchange rate, minimum wage). Each example is linked to the mechanism. Mentioning stagflation shows awareness of the consequences.

Likely Score4 / 4

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