Deflationary Gap in AD-AS Model Quiz

In the AD-AS diagram, a deflationary gap appears when the intersection of the AD and SRAS curves falls to the left of the vertical LRAS line. This means the current equilibrium real GDP is less than potential GDP. The economy is producing below its maximum sustainable capacity, with unemployment above the natural rate and downward pressure on the price level from weak demand.

This accurately describes how a deflationary gap appears in the AD-AS framework. When aggregate demand declines, perhaps due to a collapse in consumer confidence or a sharp fall in business investment, the AD curve shifts left. The new intersection with the SRAS falls below and to the left of the vertical LRAS, indicating actual GDP is below potential. This graphical position confirms the existence and magnitude of the deflationary gap.

The self-correction mechanism for a deflationary gap operates through labor markets. High unemployment puts downward pressure on wages. As nominal wages fall, production costs for firms decline, making it profitable to expand output. This gradually shifts the SRAS to the right. The economy moves along the AD curve to a new intersection with the SRAS that is closer to or at the LRAS, restoring output to potential at a lower price level.

As the SRAS shifts right due to falling wages and costs, two things happen simultaneously. More output is produced at each price level, so real GDP rises toward potential. However, the lower costs that enabled the shift mean prices also fall from their current level. The economy moves to a new equilibrium with higher real output and a lower price level, restoring output to potential while reflecting the disinflationary adjustment of the self-correction process.

Starting from long-run equilibrium where AD, SRAS, and LRAS intersect, if AD shifts leftward due to a shock such as falling consumer confidence or reduced investment, the new intersection with the SRAS lies to the left of the LRAS. Actual GDP falls below potential, creating a deflationary gap. This graphical shift illustrates how demand-side shocks translate into below-potential output and represents the standard way a deflationary gap forms in the AD-AS framework.

To close a deflationary gap, aggregate demand must increase so that the AD-SRAS intersection moves rightward to the LRAS line. Increasing government spending directly adds to aggregate demand, shifting the AD curve to the right. As the new AD intersects SRAS closer to the LRAS, actual GDP rises toward potential, unemployment falls, and the deflationary gap narrows. This is the direct fiscal stimulus mechanism for closing a deflationary gap in the AD-AS model.

When the SRAS shifts right due to falling wages, the economy finds a new long-run equilibrium at potential GDP but at a lower price level than before the deflationary gap formed. The wages and costs that fell during the adjustment remain lower, keeping prices below their original level. This is the deflationary legacy of the self-correction process and explains why economists are sometimes concerned about the deflationary consequences of prolonged recessionary gaps.

The deflationary gap is graphically represented as the AD-SRAS intersection to the left of the LRAS, confirming below-potential output. Self-correction occurs through falling wages shifting the SRAS rightward. Full equilibrium is restored only when all three curves intersect at potential GDP. The claim that actual GDP is above potential describes an inflationary gap, not a deflationary one. Incorrect identification of the gap direction is one of the most common errors in AD-AS analysis.

Nominal wages tend to be sticky downward in practice. Workers resist pay cuts, and employers are often reluctant to impose them to maintain morale and productivity. Long-term contracts lock wages in place for extended periods. These real-world rigidities slow the decline in wages that would trigger the rightward SRAS shift needed for self-correction. As a result, the deflationary gap may persist much longer than the model predicts, strengthening the case for active expansionary policy.

Long-run equilibrium in the AD-AS model is achieved at the intersection of all three curves at potential GDP. The deflationary gap is the horizontal distance between the current AD-SRAS intersection and this equilibrium point, measured along the real GDP axis. A larger gap means actual output is further from potential. Policy aims to shift the AD curve rightward to reduce or eliminate this distance, restoring the economy to its long-run sustainable equilibrium.

The business cycle trough is the point of deepest recession, where real GDP has fallen the most relative to its trend. In the AD-AS model, this corresponds to the maximum deflationary gap, where the distance between the AD-SRAS intersection and the LRAS is largest. As the economy begins its recovery, either through self-correction or expansionary policy, the gap narrows, and real GDP moves back toward potential from the trough.

Expansionary fiscal policy shifts the AD curve rightward. As the economy moves up along the SRAS toward the LRAS, actual GDP rises toward potential and unemployment falls. The price level rises somewhat because the upward-sloping SRAS means higher output comes at a higher price. The LRAS does not shift in response to demand changes; it only moves when the economy's productive capacity changes through supply-side improvements.

The position of the AD-SRAS intersection relative to the vertical LRAS determines the type of gap. A deflationary gap has its intersection to the left of the LRAS, meaning actual output is below potential. An inflationary gap has its intersection to the right, meaning actual output is above potential. This graphical distinction is fundamental to correctly diagnosing the state of the economy and determining the appropriate direction of policy response.

The self-correction of a deflationary gap does not occur through a rightward shift of the AD curve. It operates through a rightward shift of the SRAS curve driven by falling wages and reduced production costs. As wages fall due to high unemployment, businesses face lower costs, making it profitable to expand output. The economy moves along the existing AD curve to a new, higher real GDP level as the SRAS shifts right, not through any automatic rightward shift of aggregate demand.

The vertical LRAS line is the reference point for identifying and measuring the deflationary gap. It marks potential GDP, the economy's sustainable full-employment output level. The deflationary gap is the distance between current actual GDP, shown by the AD-SRAS intersection, and the potential GDP marked by the LRAS. Policy success is measured by how much the AD curve has been shifted rightward toward the LRAS line, reducing the gap between actual and potential output.