The concept and types of aggregate supply curves

Aggregate supply represents the total volume of goods and services that firms in an economy are willing and able to produce at a given price level over a specific period.

Short-run aggregate supply (SRAS) curve

This curve slopes upwards from left to right, showing that higher price levels encourage firms to increase output. A price-inelastic SRAS curve is steep, meaning output rises little with price increases. A price-elastic SRAS curve is flatter, indicating a greater output response to rising prices.

Long-run aggregate supply (LRAS) curve

This curve is vertical, reflecting the economy's full capacity where all resources are fully utilised. Changes in price levels do not affect output in the long run, as the economy adjusts to equilibrium at maximum production.

Factors causing shifts in short-run aggregate supply

Shifts in the SRAS curve occur due to changes in the costs of production, which alter the quantity of output firms can supply at any given price level.

Causes of rightward shifts in SRAS

A rightward shift increases output at the same price level, often resulting from reduced production costs.

• Lower wage rates, which decrease labour expenses.
• Reduced business taxes, easing financial burdens on firms.
• Favourable exchange rates, making imported inputs cheaper.
• Improved efficiency levels, such as through better technology or processes.

Causes of leftward shifts in SRAS

A leftward shift decreases output at the same price level, typically from higher production costs.

• Rising wage rates, increasing overall expenses.
• Higher business taxes, adding to operational costs.
• Unfavourable exchange rates, raising the price of imported materials.
• Reduced efficiency levels, perhaps due to outdated equipment.
• Supply-side shocks, such as natural disasters or international conflicts, which suddenly reduce available resources or disrupt production.

Factors influencing long-run aggregate supply

The LRAS curve shows the economy's maximum productive capacity, determined by the quantity and quality of factors of production like land, labour, capital, and enterprise. Shifts in LRAS reflect changes in this capacity.

Improvements shifting LRAS rightwards

These enhancements increase the economy's potential output, leading to long-run economic growth.

• Better education and skills development, enhancing workforce productivity.
• Demographic changes, such as immigration of skilled workers expanding the labour pool.
• Discovery of new resources, providing more inputs for production.
• Healthcare improvements, resulting in a healthier workforce with extended productive years.
• Streamlined government regulations, reducing bureaucratic obstacles.
• Increased market competition, forcing inefficient firms to exit and improving overall efficiency.
• Enterprise promotion through incentives like grants or tax breaks for new businesses.
• Greater factor mobility, achieved via training programmes that help workers switch occupations or locations.

Deteriorations shifting LRAS leftwards

These reductions lower the economy's maximum output.

• Shortages of key resources, limiting production capacity.
• Declines in workforce skills or size, such as through emigration or inadequate training.
• Worsening health standards, reducing labour productivity.
• Increased regulations that hinder business operations.
• Reduced competition, allowing inefficiencies to persist.

The accelerator effect and its relationship with the multiplier

The accelerator effect describes how changes in national income influence business investment in capital goods.

Key features of the accelerator effect

• Businesses base investment decisions on the rate of change in national income.
• Rapid growth in national income prompts higher investment to expand production capacity, especially during economic recovery or the start of a boom.
• Rising demand signals the need for more capital goods, like machinery, to meet future output requirements.
• This effect interacts with the multiplier, amplifying economic changes.

The accelerator-multiplier relationship in economic cycles

• During economic growth - An initial rise in aggregate demand leads to increased investment (accelerator effect), which then boosts aggregate demand further through the multiplier, creating multiplied growth in national income and encouraging even more investment.
• During economic contraction - Falling demand reduces investment, triggering a reverse multiplier effect that deepens the downturn, leading to cyclical patterns in the economy.

The Keynesian perspective on aggregate supply

Keynesian economists offer an alternative view of long-run aggregate supply, presenting it as an L-shaped curve rather than the vertical classical model. This shape accounts for varying levels of spare capacity and resource utilisation.

Sections of the Keynesian LRAS curve

• Horizontal section (completely elastic) - At low output levels, the curve is flat, indicating abundant spare capacity. Firms can increase production without raising prices, often due to high unemployment allowing easy hiring.
• Upward-sloping section - As output rises, bottlenecks emerge, such as shortages of skilled labour or materials, causing costs and prices to increase gradually.
• Vertical section (completely inelastic) - At full capacity, the curve becomes vertical, as all resources are fully employed, preventing further output increases regardless of price rises.