The concept and types of aggregate supply curves

Aggregate supply represents the total volume of goods and services produced within an economy at a specific price level over a defined timeframe. It is depicted through two main types of curves, reflecting different time perspectives and economic conditions.

Short-run aggregate supply (SRAS)

This curve slopes upwards from left to right, indicating that as the price level rises, firms are willing to produce more output.

The shape of the curve differs depending on:

• If SRAS is price inelastic - The curve is steep, showing limited output increase with price rises.
• If SRAS is price elastic - The curve is flatter, indicating a larger output increase as prices go up.

Long-run aggregate supply (LRAS)

This curve is vertical, often referred to as the 'neo-classical' view. It shows that in the long run, the economy operates at full capacity, and output remains constant regardless of price level changes, as all resources are fully utilised.

Factors causing shifts in short-run aggregate supply

The SRAS curve moves when there are changes in production costs, affecting the amount of output firms can produce at a given price level.

Influences on SRAS shifts

• Reduction in production costs - Lower costs, such as a drop in raw material prices (e.g., oil prices falling), shift SRAS to the right, allowing more output at the same price level. For instance, output might rise from Y to Y_A at a constant price.
• Specific cost factors - Changes in wage levels, business taxes, exchange rates, and overall efficiency can cause shifts in the SRAS curve.
• Supply-side shocks - Unexpected events like natural disasters or conflicts can suddenly decrease aggregate supply, shifting SRAS left and often increasing prices.

Factors influencing long-run aggregate supply

The LRAS curve reflects the economy's maximum productive capacity, determined by the availability and quality of factors of production. Shifts in LRAS indicate changes in this capacity.

Improvements in factors of production

Enhancements increase capacity, shifting LRAS to the right (e.g., from Yf to Yf_B), indicating economic growth.

Examples of enhancements that shift LRAS to the right:

• Technological advancements through investment in innovation.
• Better education and skills training, boosting worker productivity.
• Demographic boosts, such as skilled immigration increasing the labour force.
• Discovery of new resources, expanding potential output.
• Health improvements, reducing worker absenteeism and extending working life.
• Regulatory reforms, such as cutting unnecessary bureaucracy.
• Increased competition, driving out inefficient firms.
• Policies promoting enterprise, like incentives for startups.
• Enhanced factor mobility, such as retraining to reduce occupational immobility.

Deterioration in factors of production

A decline, such as a severe shortage of critical resources (e.g., oil), shifts LRAS to the left, reducing maximum output.

The Keynesian perspective on aggregate supply

Keynesian economists propose a different view of long-run aggregate supply, suggesting it is not simply vertical but follows an L-shaped pattern, reflecting varied economic conditions.

Characteristics of the Keynesian LRAS curve

• Horizontal section (elastic supply) - At low output levels, the curve is flat, showing spare capacity in the economy. Output can increase without raising prices, often due to high unemployment allowing firms to hire without cost increases.
• Upward sloping section (supply bottlenecks) - As output rises, the curve slopes up, indicating supply constraints like labour or material shortages, which drive up costs and prices.
• Vertical section (inelastic supply) - At full capacity, the curve becomes vertical, showing no further output increase is possible as all resources are fully employed.

Causes of short-run and long-run economic growth

Economic growth can occur in both the short run and long run, driven by different factors affecting aggregate supply.

Short-run economic growth

An increase (rightward shift) in the SRAS curve, often due to falling production costs, can lead to short-run growth.

Examples include:

• A decrease in energy costs, such as a drop in oil prices.
• A reduction in wage levels, lowering overall expenses for firms.

Long-run economic growth

An increase in productive potential from supply-side improvements that enhance the economy's capacity can cause long-run growth.

Key factors include:

• Innovation, such as developing new production technologies.
• Investment in modern equipment and infrastructure (capital stock).
• Agricultural advancements, like adopting genetically modified crop varieties.
• Boosting human capital through increased education and training budgets.
• Expanding the workforce, for instance, through immigration policies.
• Government role in creating a stable economic environment through sound policies, which supports sustained long-run growth by encouraging investment and confidence.