Aggregate Demand and Aggregate Supply Review

Review sections 7.2 and 7.3 of Chapter 7 in order to examine the relationship between the labor market dynamics and the achievement of equlibrium in the short run and the long run. Note the role of wage and price stickiness.

7.3 Recessionary and Inflationary Gaps and Long-Run

A Shift in Short-Run Aggregate Supply: An Increase in the Cost of Health Care

Again suppose, with an aggregate demand curve at AD1 and a short-run aggregate supply at SRAS1, an economy is initially in equilibrium at its potential output YP, at a price level of P1, as shown in Figure 7.13 "Long-Run Adjustment to a Recessionary Gap". Now suppose that the short-run aggregate supply curve shifts owing to a rise in the cost of health care. As we explained earlier, because health insurance premiums are paid primarily by firms for their workers, an increase in premiums raises the cost of production and causes a reduction in the short-run aggregate supply curve from SRAS1 to SRAS2.

Figure 7.13 Long-Run Adjustment to a Recessionary Gap

A decrease in aggregate supply from SRAS1 to SRAS2 reduces real GDP to Y2 and raises the price level to P2, creating a recessionary gap of YP − Y2. In the long run, as prices and nominal wages decrease, the short-run aggregate supply curve moves back to SRAS1 and real GDP returns to potential.

As a result, the price level rises to P2 and real GDP falls to Y2. The economy now has a recessionary gap equal to the difference between YP and Y2. Notice that this situation is particularly disagreeable, because both unemployment and the price level rose.

With real GDP below potential, though, there will eventually be pressure on the price level to fall. Increased unemployment also puts pressure on nominal wages to fall. In the long run, the short-run aggregate supply curve shifts back to SRAS1. In this case, real GDP returns to potential at YP, the price level falls back to P1, and employment returns to its natural level. These adjustments will close the recessionary gap.

How sticky prices and nominal wages are will determine the time it takes for the economy to return to potential. People often expect the government or the central bank to respond in some way to try to close gaps. This issue is addressed next.