Difference Between Short Run and Long Run Aggregate Supply Quiz

The SRAS slopes upward because wages and some input prices are rigid in the short run. When the price level rises, firms can earn more without their costs immediately rising proportionally, incentivizing them to increase output. In the long run, wages and all costs adjust fully to price level changes. This eliminates the short-run profit incentive to produce more, making the LRAS vertical at potential output.

Wage stickiness is a central concept in the short-run aggregate supply model. Workers and employers often enter into contracts that fix wages for a period of time. Even when the price level changes, wages may not adjust immediately due to contracts, social norms, or information lags. This stickiness means that when output prices rise faster than wages, firms find it profitable to increase production, giving the SRAS its upward slope.

A supply shock like rising oil prices increases production costs across the economy, shifting the SRAS to the left because firms produce less at every price level. However, the LRAS reflects the economy's fundamental productive capacity determined by labor, capital, and technology. If the oil price shock is temporary or the economy adapts, the LRAS is unaffected. A permanent destruction of productive capacity would shift the LRAS.

In a recessionary gap, the aggregate demand curve intersects the SRAS curve at a point where real GDP is less than potential. This intersection falls to the left of the vertical LRAS line. The economy is producing below its sustainable capacity, with unemployment above the natural rate. Over time, falling wages shift the SRAS to the right until the economy returns to the LRAS at potential output.

A recessionary gap is closed through a rightward, not leftward, shift of the SRAS. When unemployment is above the natural rate, wages fall, reducing production costs. This rightward shift of the SRAS increases output and lowers the price level until the economy returns to potential GDP. A leftward shift of the SRAS would worsen the recessionary gap rather than close it.

When aggregate demand increases from a position of full employment, firms respond by increasing output in the short run because wages and costs have not yet risen. Real GDP temporarily exceeds potential. However, over time, tight labor markets push wages up, increasing costs and shifting the SRAS to the left, returning output to potential at a higher price level. This describes the transition from the SRAS response to the LRAS equilibrium.

The SRAS slopes upward due to short-run price and wage stickiness. It shifts when input costs change, such as when oil prices or wages rise, because these alter the cost structure for all producers. The SRAS intersects the vertical LRAS at long-run equilibrium. The claim that the SRAS is unaffected by input costs is incorrect since cost changes are the primary driver of SRAS shifts.

When the economy operates above potential in an inflationary gap, unemployment is below the natural rate and workers can bargain for higher wages. Rising wages increase costs, shifting the SRAS to the left. This process reduces output and raises prices until the economy returns to its long-run equilibrium at potential GDP. This self-correcting mechanism operates through the labor market without requiring government intervention.

The self-correcting mechanism works through the flexibility of wages and prices over time. In the short run, wages are sticky and output may deviate from potential. Over time, wages and input prices adjust, shifting the SRAS until the economy returns to long-run equilibrium at potential GDP on the LRAS. This long-run adjustment eliminates deviations from potential without requiring any specific policy action.

Stagflation describes the combination of rising prices and falling output, and it occurs when the SRAS shifts to the left due to a negative supply shock. When oil prices rise sharply, production costs increase across the economy. Firms supply less at every price level, moving the economy to a higher price level and lower real output. This simultaneous deterioration in both inflation and output is a defining feature of supply-side recessions.

In the AS-AD model, long-run equilibrium is reached when actual GDP equals potential GDP. This occurs at the intersection of the AD curve and the vertical LRAS, and the SRAS must also pass through this same point for the economy to be in full equilibrium. At this junction, all markets clear, wages and prices have fully adjusted, and neither inflationary nor recessionary gaps exist.

The SRAS captures short-run output responsiveness to price changes due to sticky wages, while the LRAS reflects the long-run equilibrium at potential output where all prices adjust. The LRAS is vertical precisely because full price flexibility eliminates any lasting connection between price levels and real output. Using only the SRAS for long-run analysis is incorrect because it does not capture the full adjustment of wages and prices.

Supply-side recessions occur when the SRAS shifts to the left due to rising input costs. A sharp increase in oil prices raises production costs for virtually all businesses, reducing output at every price level. This shifts the SRAS leftward, simultaneously reducing real GDP and raising the price level in a pattern of stagflation. This contrasts with demand-side recessions where falling aggregate demand reduces both output and prices.

Only the SRAS shifts in response to changes in input costs. When wages or energy prices rise, production costs increase across the economy, shifting the SRAS to the left. The LRAS, however, only shifts when the economy's fundamental productive capacity changes through factors like capital accumulation, labor force growth, or technological progress. Input cost changes are short-run supply-side factors that affect the SRAS, not the LRAS.

Together, the SRAS and LRAS provide a complete picture of macroeconomic behavior. The SRAS explains how output and prices respond in the short run to demand and supply shocks, including the business cycle. The LRAS anchors the economy's long-run equilibrium at potential GDP. Rightward shifts of the LRAS over time, driven by capital accumulation, workforce growth, and technological progress, represent genuine and sustainable long-run economic growth.