Inflationary Gap AD AS Model Quiz: Excess Demand in AD-AS

In the AD-AS model, an inflationary gap is visible when the intersection of the AD and SRAS curves lies to the right of the vertical LRAS. This means actual real GDP exceeds potential GDP, confirming the economy is overproducing. The price level at this intersection is above the long-run equilibrium level, consistent with inflationary pressure as the economy operates beyond its sustainable productive capacity.

This is the standard graphical representation of an inflationary gap. When the AD and SRAS curves meet at a level of real GDP that is beyond the economy's potential, the intersection lies to the right of the vertical LRAS line. The resulting price level is higher than the long-run equilibrium, reflecting the inflationary pressure that arises when actual spending and output push the economy beyond its sustainable full-employment capacity.

The self-correction mechanism operates through the labor market. When output exceeds potential, unemployment falls below the natural rate and wages rise. Higher wages increase production costs, shifting the SRAS to the left. As the SRAS shifts left, real output falls back toward potential and the price level rises further. Long-run equilibrium is restored when the SRAS, LRAS, and AD all intersect at the same point.

In an inflationary gap shown on an AD-AS diagram, the current equilibrium, where AD meets SRAS, sits to the right of the vertical LRAS line. Actual GDP exceeds potential GDP, placing the economy beyond the long-run equilibrium. The price level is above its long-run sustainable level, reflecting the inflationary consequence of operating beyond potential. This graphical positioning distinguishes the inflationary gap from both equilibrium and recessionary gap conditions.

Starting from long-run equilibrium where the AD, SRAS, and LRAS all intersect, if the AD curve shifts to the right due to increased consumer spending, government stimulus, or investment, the new intersection with the SRAS lies to the right of the LRAS. This means actual GDP has risen above potential, creating an inflationary gap. The rightward AD shift is the standard trigger for an inflationary gap in the AD-AS framework.

As rising wages shift the SRAS to the left, firms supply less at every price level and the price level rises further. Output falls back toward potential GDP, but the economy settles at a higher long-run price level than before the inflationary gap developed. This is the inflationary legacy of the gap: even after self-correction, the price level is permanently higher than it was before the demand surge created the gap.

To eliminate an inflationary gap, aggregate demand must be reduced so that it no longer pushes output above potential. A leftward shift of the AD curve, caused by contractionary fiscal or monetary policy, moves the intersection of AD and SRAS back to the LRAS line. Real output returns to potential GDP and the upward pressure on the price level is relieved. This is the direct policy mechanism for closing an inflationary gap in the AD-AS framework.

The inflationary gap is shown as the AD-SRAS intersection to the right of the LRAS. Self-correction occurs through rising wages shifting the SRAS leftward until all three curves intersect at potential GDP. The LRAS does not shift to accommodate excess output; it remains fixed at potential. Only genuine supply-side improvements such as new technology or capital would shift the LRAS to the right.

When an inflationary gap exists, the economy is operating to the right of the LRAS at a price level above the long-run equilibrium. The excess demand that created the gap has pushed the price level higher than it would be at potential GDP. As self-correction occurs through rising SRAS costs shifting output back to potential, the price level rises even further to a new, higher long-run equilibrium reflecting the inflationary legacy of the demand surge.

When all three curves intersect at the same point, the economy is in long-run equilibrium. Actual GDP equals potential GDP, meaning output is at its maximum sustainable level. Unemployment equals the natural rate, and there are no inflationary or recessionary pressures. This triple intersection is the reference point from which inflationary and recessionary gaps are defined, and it is the target that both self-correction mechanisms and stabilization policies aim to restore.

At the peak of the business cycle, the economy has expanded beyond its long-run sustainable capacity. Actual GDP exceeds potential GDP, placing the economy in an inflationary gap. This is consistent with what is observed at peaks: unemployment at or below the natural rate, rising wages and prices, and strong aggregate demand. Following the peak, the self-correcting mechanism or contractionary policy brings output back toward potential.

The long-run correction of an inflationary gap works through the labor market. Tight conditions drive wages higher, increasing production costs and shifting the SRAS leftward. As the SRAS shifts, output falls back to potential but the price level settles permanently higher. The AD curve does not shift to the right during self-correction; that would deepen the gap. The AD-driven shift that created the gap is separate from the supply-side adjustment that closes it.

The self-correcting mechanism for an inflationary gap depends on rising wages shifting the SRAS to the left. If wages are slow to adjust upward due to long-term contracts, social norms, or labor market rigidities, the SRAS shifts leftward slowly. This means the inflationary gap persists longer, with sustained overproduction and continued inflation until wages eventually catch up and the adjustment process completes.

Contractionary policy can close an inflationary gap faster than the self-correction mechanism because policy acts deliberately and can be implemented quickly, while wage and price adjustments in the self-correction process take time. The self-correction mechanism operates through gradual wage increases, which may be slow due to wage stickiness. By directly reducing aggregate demand, contractionary policy brings output back to potential more swiftly, minimizing the duration and cost of sustained inflation.

In the long run, rising wages from the tight labor market shift the SRAS to the left, gradually returning actual GDP to potential. However, the price level does not return to its original level. It stabilizes at a new, higher equilibrium because the inflationary pressures from the gap have permanently raised the overall price level. The economy returns to sustainable output but retains the inflation generated by the period of overproduction.