The difference between the short run and long run in macroeconomics

Macroeconomics examines how entire economies behave, including concepts like output, employment, and price levels. Two key time frames help explain these behaviors: the short run and the long run. These periods differ based on how flexible prices and wages are in response to changes.

Key differences between short run and long run

• Short run - A period where some input prices, such as wages, are fixed and do not adjust quickly to economic changes. This stickiness can lead to temporary imbalances, like higher unemployment during a downturn.
• Long run - A period where all prices and wages are fully flexible, meaning they can adjust completely to economic shifts. As a result, the economy returns to balance without ongoing trade-offs, such as between inflation (a general rise in price levels) and unemployment (the state where people who are able and willing to work cannot find jobs).

This flexibility in the long run means there is no lasting trade-off between inflation and unemployment. For example, while short-run policies might temporarily reduce unemployment by accepting higher inflation, these effects fade as prices and wages adjust over time.

The definition and graph of the long-run aggregate supply curve

The aggregate supply (AS) curve shows the total quantity of goods and services that firms in an economy are willing to produce at different price levels. Within this model, the long-run aggregate supply (LRAS) curve focuses on the economy's output potential over an extended period.

The LRAS curve represents the maximum sustainable capacity of an economy, which is the total output produced when all resources are fully employed. It is graphed with the price level on the vertical axis and real gross domestic product (GDP), a measure of total output adjusted for inflation, on the horizontal axis.

Graphing the LRAS curve

The LRAS curve is a vertical line at the full-employment level of output. This positioning indicates that in the long run, the economy's output does not depend on the price level but on factors like technology, labor force size, and capital stock.

For instance, if an economy's full-employment output is $18 trillion in real GDP, the LRAS curve would be drawn as a straight vertical line at that point on the graph, regardless of whether prices are high or low.

Why the LRAS curve is vertical

The vertical shape of the LRAS curve reflects key economic principles in the long run. Unlike the short-run aggregate supply curve, which slopes upward because some prices are fixed, the LRAS remains vertical due to complete adjustments in the economy.

Reasons for the vertical shape

• Full adjustment of wages and prices - In the long run, all wages and prices can change freely. If demand increases and pushes prices up, firms might initially produce more, but eventually, workers demand higher wages to match rising costs. This adjustment brings output back to its sustainable level.
• No response to price level changes - Output stays at the full-employment level because resources are fully utilized. Higher prices do not create more resources or productivity; they simply redistribute income without expanding total output.
• Focus on real factors - The curve's position depends on real economic variables, such as the quantity and quality of labor, capital, and technology, rather than nominal factors like the overall price level.

As a result, shifts in aggregate demand (the total demand for goods and services) affect only the price level in the long run, not the output level. For example, an increase in government spending might raise prices but won't push output beyond full employment sustainably.

The connection between LRAS and the production possibilities curve

The LRAS curve is closely linked to another key economic model: the production possibilities curve (PPC), which illustrates the maximum combinations of two goods an economy can produce with full resource use.

Both the LRAS and PPC represent the economy's maximum sustainable capacity, assuming all resources—like labor, capital, and natural resources—are fully employed.

Similarities between LRAS and PPC

• Full employment focus - Each shows output when resources are used efficiently without waste. The PPC highlights trade-offs between goods, while LRAS aggregates this into total output.
• Vertical nature at capacity - Just as the PPC is a frontier beyond which production is impossible without growth, the LRAS is vertical to show that output can't exceed full-employment levels in the long run.
• Shifts due to growth factors - Both shift rightward with improvements like better technology or more workers, increasing potential output. For instance, investing in education could expand the PPC outward and shift the LRAS to the right.

This connection helps explain how long-run economic growth expands an economy's potential, moving beyond short-run fluctuations captured in models like the aggregate demand-aggregate supply (AD-AS) framework.