1. PowerPoint Lectures for
Principles of Macroeconomics, 9e By
Karl E. Case, Ray C. Fair & Sharon M. Oster

3. Aggregate Supply and the Equilibrium Price Level
Prepared by:
Fernando & Yvonn Quijano

4. 13 11 Aggregate Supply and the Equilibrium Price Level
PART III THE CORE OF MACROECONOMIC THEORY 13 11
CHAPTER OUTLINE
The Aggregate Supply Curve
The Aggregate Supply Curve: A Warning
Aggregate Supply in the Short Run
Shifts of the Short-Run Aggregate Supply Curve
The Equilibrium Price Level
The Long-Run Aggregate Supply Curve Potential GDP
Monetary and FiscalPolicy Effects Long-Run Aggregate Supply and Policy Effects
Causes of Inflation Demand-Pull Inflation Cost-Push, or Supply-Side, Inflation Expectations and Inflation Money and Inflation Sustained Inflation as a Purely Monetary Phenomenon
The Behavior of the Fed Controlling the Interest Rate The Fed’s Response to the State of the Economy Fed Behavior Since 1970 Inflation Targeting
Looking Ahead

5. The Aggregate Supply Curve
aggregate supply The total supply of all goods and services in an economy.
The Aggregate Supply Curve: A Warning
aggregate supply (AS) curve A graph that shows the relationship between the aggregate quantity of output supplied by all firms in an economy and the overall price level.
An “aggregate supply curve” in the traditional sense of the word supply does not exist. What does exist is what we might call a “price/output response” curve—a curve that traces out the price decisions and output decisions of all firms in the economy under a given set of circumstances.

6. The Aggregate Supply Curve
Aggregate Supply in the Short Run
 FIGURE The Short-Run Aggregate Supply Curve
In the short run, the aggregate supply curve (the price/output response curve) has a positive slope.
At low levels of aggregate output, the curve is fairly flat.
As the economy approaches capacity, the curve becomes nearly vertical.
At capacity, the curve is vertical.

7. The Aggregate Supply Curve
Shifts of the Short-Run Aggregate Supply Curve
cost shock, or supply shock A change in costs that shifts the short-run aggregate supply (AS) curve.
 FIGURE Shifts of the Short-Run Aggregate Supply Curve

8. The Equilibrium Price Level
equilibrium price level The price level at which the aggregate demand and aggregate supply curves intersect.
 FIGURE The Equilibrium Price Level
At each point along the AD curve, both the money market and the goods market are in equilibrium. Each point on the AS curve represents the price/ output decisions of all the firms in the economy.
P0 and Y0 correspond to equilibrium in the goods market and the money market and to a set of price/output decisions on the part of all the firms in the economy.

9. The Long-Run Aggregate Supply Curve
 FIGURE The Long-Run Aggregate Supply Curve
When the AD curve shifts from AD0 to AD1, the equilibrium price level initially rises from P0 to P1 and output rises from Y0 to Y1.
Wages respond in the longer run, shifting the AS curve from AS0 to AS1.
If wages fully adjust, output will be back at Y0. Y0 is sometimes called potential GDP.

10. The Simple “Keynesian” Aggregate Supply Curve
The Long-Run Aggregate Supply Curve
The Simple “Keynesian” Aggregate Supply Curve
One view of the aggregate supply curve, the simple “Keynesian” view, holds that at any given moment, the economy has a clearly defined capacity, or maximum, output.
With planned aggregate expenditure of AE1 and aggregate demand of AD1, equilibrium output is Y1.
A shift of planned aggregate expenditure to AE2, corresponding to a shift of the AD curve to AD2, causes output to rise but the price level to remain at P1.
If planned aggregate expenditure and aggregate demand exceed YF, however, there is an inflationary gap and the price level rises to P3.

11. The Long-Run Aggregate Supply Curve
Potential GDP
potential output, or potential GDP The level of aggregate output that can be sustained in the long run without inflation.
Short-Run Equilibrium Below Potential Output
Although different economists have different opinions on how to determine whether an economy is operating at or above potential output, there is general agreement that there is a maximum level of output (below the vertical portion of the short-run aggregate supply curve) that can be sustained without inflation.

12. Monetary and Fiscal Policy Effects
 FIGURE A Shift of the Aggregate Demand Curve When the Economy Is on the Nearly Flat Part of the AS Curve
Aggregate demand can shift to the right for a number of reasons, including an increase in the money supply, a tax cut, or an increase in government spending.
If the shift occurs when the economy is on the nearly flat portion of the AS curve, the result will be an increase in output with little increase in the price level from point A to point A’.

13. Monetary and Fiscal Policy Effects
 FIGURE A Shift of the Aggregate Demand Curve When the Economy Is Operating at or Near Maximum Capacity
If a shift of aggregate demand occurs while the economy is operating near full capacity, the result will be an increase in the price level with little increase in output from point B to point B’.

14. Monetary and Fiscal Policy Effects
Long-Run Aggregate Supply and Policy Effects
It is important to realize that if the AS curve is vertical in the long run, neither monetary policy nor fiscal policy has any effect on aggregate output in the long run.
The conclusion that policy has no effect on aggregate output in the long run is perhaps startling.

15. Causes of Inflation Demand-Pull Inflation
demand-pull inflation Inflation that is initiated by an increase in aggregate demand.

16. Causes of Inflation Cost-Push, or Supply-Side, Inflation
cost-push, or supply-side, inflation Inflation caused by an increase in costs.
 FIGURE Cost-Push, or Supply-Side, Inflation
An increase in costs shifts the AS curve to the left.
By assuming the government does not react to this shift, the AD curve does not shift, the price level rises, and output falls.

17. Causes of Inflation Cost-Push, or Supply-Side, Inflation
stagflation Occurs when output is falling at the same time that prices are rising.
 FIGURE Cost Shocks Are Bad News for Policy Makers
A cost shock with no change in monetary or fiscal policy would shift the aggregate supply curve from AS0 to AS1, lower output from Y0 to Y1, and raise the price level from P0 to P1.
Monetary or fiscal policy could be changed enough to have the AD curve shift from AD0 to AD1.
This policy would raise aggregate output Y again, but it would raise the price level further, to P2.

18. Causes of Inflation Expectations and Inflation
When firms are making their price/output decisions, their expectations of future prices may affect their current decisions. If a firm expects that its competitors will raise their prices, in anticipation, it may raise its own price.
Given the importance of expectations in inflation, the central banks of many countries survey consumers about their expectations.

19. Causes of Inflation Money and Inflation
 FIGURE Sustained Inflation From an Initial Increase in G and Fed Accommodation
An increase in G with the money supply constant shifts the AD curve from AD0 to AD1. Although not shown in the figure, this leads to an increase in the interest rate and crowding out of planned investment.
If the Fed tries to keep the interest rate unchanged by increasing the money supply, the AD curve will shift farther and farther to the right. The result is a sustained inflation, perhaps even hyperinflation.

20. Causes of Inflation
Sustained Inflation as a Purely Monetary Phenomenon
Virtually all economists agree that an increase in the price level can be caused by anything that causes the AD curve to shift to the right or the AS curve to shift to the left.
It is also generally agreed that for a sustained inflation to occur, the Fed must accommodate it.
In this sense, a sustained inflation can be thought of as a purely monetary phenomenon.

21. The Behavior of the Fed
 FIGURE Fed Behavior

22. The Behavior of the Fed Controlling the Interest Rate
The buying and selling of government securities by the Fed has two effects at the same time: It changes the money supply, and it changes the interest rate.
How much the interest rate changes depends on the shape of the money demand curve. The steeper the money demand curve, the larger the change in the interest rate for a given size change in government securities.
If the Fed wants to achieve a particular value of the money supply, it must accept whatever interest rate value is implied by this choice. Conversely, if the Fed wants to achieve a particular value of the interest rate, it must accept whatever money supply value is implied by this.

23. The Behavior of the Fed The Fed’s Response to the State of the Economy
 FIGURE The Fed’s Response to Low Output/Low Inflation
During periods of low output/low inflation, the economy is on the relatively flat portion of the AS curve. In this case, the Fed is likely to lower the interest rate (and thus expand the money supply).
This will shift the AD curve to the right, from AD0 to AD1, and lead to an increase in output with very little increase in the price level.

24. The Behavior of the Fed The Fed’s Response to the State of the Economy
 FIGURE The Fed’s Response to High Output/High Inflation
During periods of high output/high inflation, the economy is on the relatively steep portion of the AS curve. In this case, the Fed is likely to increase the interest rate (and thus contract the money supply).
This will shift the AD curve to the left, from AD0 to AD1, and lead to a decrease in the price level with very little decrease in output.

25. The Behavior of the Fed Fed Behavior Since 1970
 FIGURE Output, Inflation, and the Interest Rate 1970 I–2007 IV
The Fed generally had high interest rates in the two inflationary periods and low interest rates from the mid 1980s on. It aggressively lowered interest rates in the 1990 IV–1991 I and 2001 I–2001 III recessions. Output is the percentage deviation of real GDP from its trend. Inflation is the 4-quarter average of the percentage change in the GDP deflator. The interest rate is the 3- month Treasury bill rate.

26. Rising Food Prices Worry Central Banks Around the World
The Behavior of the Fed
Inflation Targeting
inflation targeting When a monetary authority chooses its interest rate values with the aim of keeping the inflation rate within some specified band over some specified horizon.
Rising Food Prices Worry Central Banks Around the World
Food Prices Worry Central Bankers
Wall Street Journal

27. REVIEW TERMS AND CONCEPTS
aggregate supply
aggregate supply (AS) curve
cost-push, or supply-side, inflation
cost shock, or supply shock
demand-pull inflation
equilibrium price level
inflation targeting
potential output, or potential GDP
stagflation