2.3.2 Short-Run Aggregate Supply

Edexcel A-Level Economics (9EC0) | Theme 2.3.2

Specification Coverage: Edexcel unit 2.3.2 - Short-Run Aggregate Supply. Students should be able to understand and explain what SRAS is, why the SRAS curve slopes upward, the causes of shifts in SRAS, and how changes in production costs affect the level of output firms are willing to supply.

The SRAS Curve: A Recap

Definition: Short-run aggregate supply is the total planned output of goods and services in an economy at a given price level, assuming that at least one factor of production, such as capital or technology, is fixed.

The SRAS curve is upward sloping because, in the short run, higher output leads to higher unit costs, such as overtime wages. Firms therefore need a higher price to make additional production worthwhile.

Diagram Placeholder

Hand-draw Diagram 1: The SRAS Curve.

Draw the standard upward-sloping SRAS curve with Price Level on the vertical axis and Real GDP on the horizontal axis.

Shifts in the SRAS Curve

A shift of the entire SRAS curve is caused by a change in the costs of production for firms across the economy.

This changes the level of output firms are willing to supply at every given price level.

Diagram showing the SRAS curve.
Figure 2: A shift of the SRAS curve to the right (SRAS1 to SRAS2) due to a decrease in production costs.

Key Factors Influencing SRAS

Factor Effect on SRAS Explanation and Chain of Analysis
Change in Costs of Raw Materials or Energy Costs up means SRAS shifts left. Costs down means SRAS shifts right. A direct change in input costs changes profitability. Higher costs mean less output can be produced at each price level.
Change in Exchange Rates An appreciation of sterling increases SRAS. A depreciation reduces SRAS. An appreciation makes imported raw materials and components cheaper, while a depreciation makes them more expensive.
Change in Indirect Taxes and Subsidies Higher taxes reduce SRAS. Higher subsidies increase SRAS. Taxes raise costs for firms, while subsidies lower costs.
Supply Shocks A negative shock reduces SRAS. A positive shock increases SRAS. Sudden events such as natural disasters, pandemics, or geopolitical conflicts can disrupt production and raise costs.

Exam Preparation

  • Draw the SRAS curve and show shifts to the left and right clearly.
  • Explain that SRAS shifts are caused by changes in costs of production.
  • Analyse specific events using a clear chain of reasoning, for example a fall in oil prices lowering production costs and shifting SRAS to the right.
  • Link this topic to cost-push inflation, because a leftward shift in SRAS raises the price level.