1. Chapter 9: Introduction to Economic Fluctuations

2. Business Cycle Changes in the level of economic activity. Real GDP has grown at an average rate of 3% per year in 1960-95 But, growth has not been smooth: –Recession: 1974-75, 1981-82, 1990-91 –Boom: 1964-69, 1983-84, 1993-95

3. Time Horizon in Macroeconomics Long run: a time period in which prices are flexible and can respond to changes in demand and supply. Prices respond to policy changes. Short-run: a time period in which prices are “sticky” at some predetermined level. Prices do not respond to policy changes.

4. Aggregate Demand The relationship between the quantity of output demanded and the price level Money market equilibrium –Money demand for transaction: (M/P) = kY –Money supply = M/P –Equilibrium: M/P = kY where k is a constant

5. Aggregate Demand Line Output, Income Price level AD An increase in the price level (P) reduces the real money balances (M/P), which lowers the quantity demanded for goods and services.

6. Shift in Aggregate Demand An increase in the money supply (M) makes the real money balances (M/P) to go up, which increases the level of the AD (this is a shift to the right) An decrease in the money supply (M) reduces lower the real money balances (M/P), which decreases the level of the AD (this is a shift to the left)

7. Shift in Aggregate Demand Output, Income Price level AD1 AD3 AD2 Increase Decrease

8. Aggregate Supply The relationship between the quantity of output supplied and the price level Long-run AS is a vertical line because of complete price flexibility assertion Short-run AS is a horizontal line because of price inflexibility assertion

9. Aggregate Supply Price level Output, Income Long-run AS Short-run AS P Y

10. Shift in Aggregate Demand Price level Output, Income AD 1 AD 2 SRAS Y1Y1 Y2Y2 In the short-run, a higher AD results in a greater output at a constant price level.

11. Shift in Aggregate Demand Price level Output, Income AD 1 LRAS P1P1 Y P2P2 AD 2 In the long-run, a higher AD results in a higher price level at a constant output.

12. Aggregate Equilibrium Price level Output, Income AD LRAS SRAS P Y

13. Effect of Stabilization Policy An increase in the money supply stimulates the investment demand, causing AD to increase Short-run effect: An increase in the level of output (point A moves to point B) Long-run effect: The rise in income increases the demand for goods, resulting in higher prices. As prices rise, output falls to its natural level (point B moves to point C)

14. Effect of Stabilization Policy Price level Output, Income AD1 LRAS SRAS P Y A AD2 B C Results of expansionary policy: Short-run: output growth Long-run: higher price level

15. Effects of a Supply Shock An increase in the production cost, reduces the short-run AS Short-run effect: A decrease in the level of output and a higher price level (point A moves to point B) Long-run effect: The decline in income decreases the demand for goods, resulting in lower prices. As prices fall, output rises to its natural level (point B moves back to A)

16. Effects of a Supply Shock Price level Output, Income AD1 LRAS SRAS1 P Y A B Results of supply shock: Short-run: output decline and price increase Long-run: higher price level SRAS2

17. Accommodating Supply Shock The offset the short-run output decline, the central bank can increase the money supply to shift the AD up The long-run effect is a permanent price increase

18. Accommodating Supply Shock Price level Output, Income AD1 LRAS SRAS1 Y A SRAS2 C AD2