The role of banks in determining long-run aggregate supply

Banks contribute to the position of the long-run aggregate supply (LRAS) curve by providing finance that supports business expansion and enhances economic capacity.

How banks influence LRAS

• Lending for investment - Firms often take loans from banks to fund purchases such as modern machinery, which boosts their ability to produce more goods and services.
• Promoting economic growth - Effective banking systems make more funds available for businesses to invest, raising the overall productive capacity of the economy.
• Shifting the LRAS curve - Improvements in the banking sector, like greater lending efficiency, move the LRAS curve to the right, indicating an increase in the economy's maximum sustainable output.

The accelerator process and investment

The accelerator process explains how changes in national income can lead to amplified shifts in investment spending by businesses.

Key features of the accelerator process

• Response to demand changes - When demand rises, firms accelerate their investment in capital goods to expand capacity and meet the expected increase in sales.
• Link to national income growth - Businesses base investment decisions on the rate at which national income is changing; rapid growth prompts substantial investment to capitalise on potential profits.
• Timing in economic cycles - This effect is most pronounced during recovery phases or the early stages of an economic boom, when demand surges and firms anticipate sustained higher output.

The interaction between the multiplier and accelerator

The multiplier and accelerator effects combine to influence economic cycles, creating patterns of expansion and contraction in output.

How the multiplier and accelerator interact

• During economic recovery - An initial rise in aggregate demand encourages firms to invest more, which then multiplies through the economy, accelerating income growth and prompting further investment.
• Amplification mechanism - The multiplier boosts the impact of investment on aggregate demand, while the accelerator responds to this faster income growth by encouraging even more capital spending.
• Reverse process in recessions - A drop in demand reduces investment, triggering a reverse multiplier that shrinks income further, leading to additional cuts in investment and a downward cycle.

This interaction helps explain why economies experience repeated fluctuations in output, with booms followed by downturns.

Characteristics of the Keynesian long-run aggregate supply curve

The Keynesian view of long-run aggregate supply (LRAS) presents it as an L-shaped curve, reflecting different economic conditions at varying output levels.

Sections of the Keynesian LRAS curve

• Horizontal section (elastic supply) - At low output, the curve is flat, showing abundant spare capacity; production can expand without raising prices, often due to high unemployment allowing easy hiring.
• Upward-sloping section (supply bottlenecks) - As output increases, the curve rises, indicating rising costs from constraints like shortages of skilled labour or key materials, which push up prices.
• Vertical section (inelastic supply) - At full capacity (Yf), the curve becomes vertical, meaning no further output growth is possible as all resources are fully utilised.

This shape highlights how supply responds differently depending on the economy's position relative to its potential.