MANKIW'S MACROECONOMICS MODULES ® MANKIW'S MACROECONOMICS MODULES CHAPTER 9 Introduction to Economic Fluctuations A PowerPointTutorial To Accompany MACROECONOMICS, 7th. Edition N. Gregory Mankiw Tutorial written by: Mannig J. Simidian B.A. in Economics with Distinction, Duke University M.P.A., Harvard University Kennedy School of Government M.B.A., Massachusetts Institute of Technology (MIT) Sloan School of Management

A recent recession began in late 2007 From the 4th quarter of 2007 to the 3rd quarter of 2008, the economy’s production of goods and services expanded by a paltry .7%-- well below the normal rate of growth. In the 4th quarter of 2008, real GDP fell at an annualized rate of 3.8 percent. The unemployment rate rose from 4.7 percent in November 2007 to 7.6 percent in January 2009. In early 2009, as this book was going to press, the end of the recession was not yet in sight, and many feared that the downturn would get significantly worse before getting better. As the book was going to press, the end of the recession was not in sight. Not surprisingly, the recession dominated the economic news of the time and the problem was high on the agenda of the newly elected president, Barack Obama.

The Business Cycle Short-run fluctuations in output and employment are called the business cycle. In previous chapters, we developed theories to explain how the economy behaves in the long run; now we’ll seek to understand how the economy behaves in the short run.

GDP and Its Componants GDP is the first place to start when analyzing the business cycle, since it is the largest gauge of economic conditions. The National Bureau of Economic Research (NBER) is the official determiner of whether the economy is suffering from a recession. A recession is usually defined by a period in which there are two consecutive declines in real GDP. In recessions, both consumption and investment decline; however, investment (business equipment, structures, new housing and inventories) is even more susceptible to decline.

Okun's Law In recessions, unemployment rises. This negative (when one rises, the other falls) relationship between unemployment and GDP is called Okun’s Law, after Arthur Okun, the economist who first studied it. In short, it is defined as: Percentage Change in Real GDP = 3.5% - 2  the Change in the Unemployment Rate If the unemployment rate remains the same, real GDP grows by about 3.5 percent. For every percentage point the unemployment rate rises, real GDP growth typically falls by 2 percent. Hence, if the unemployment rate rises from 5 to 8 percent, then real GDP growth would be: Percentage Change in Real GDP = 3.5% - 2  (8% - 5%) = - 2.5% In this case, GDP would fall by 2.5%, indicating that the economy is in a recession.

Leading Economic Indicators Many economists in business and government have the role of forecasting short-run fluctuations in the economy. One way that economists arrive at forecasts is through looking at leading indicators. Each month, the Conference Board, a private economics Research announces the index of leading economic indicators, which consists of 10 data series.

Index of Leading Economic Indicators Average workweek of production workers in manufacturing Average initial weekly claims for unemployment insurance New orders for consumer goods and materials adjusted for inflation New orders, nondefense capital goods Vendor performance New building permits issued Index of stock prices Money-supply (M2) adjusted for inflation Interest rate spread: the yield spread between 10-year Treasury notes and 3-month treasury bills 10) Index of consumer expectations

The Crystal Ball of Economic Indicators How has the crystal ball done lately? Here is what the Conference Board announced in 2007 press release: The leading index decreased sharply for the second consecutive month in November, and it has been down in four of the last six months. Most of the leading indicators contributed negatively to the index in November, led by large declines in stock prices, initial claims for unemployment insurance, index of consumer expectations, and the real money supply (M2)…The leading index fell 1.2 percent (a decline of 2.3 percent annual rate) from May to November, the largest six-month decrease in the index in six years. As predicted, the economy in 2008 and 2009 headed into a recession.

Time Horizons in Macroeconomics Classical macroeconomic theory applies to the long run but not to the short run–WHY? The short run and long run differ in terms of the treatment of prices. In the long run, prices are flexible and can respond to changes in supply or demand. In the short run, many prices are “sticky” at some predetermined level. Because prices behave differently in the short run than in the long run, economic policies have different effects over different time horizons. Let’s see this in action.

The Classical Dichotomy Recall from Chapter 4, the theoretical separation of real and nominal variables is called… The Classical Dichotomy Economists call the separation of the determinants of real and nominal variables the classical dichotomy. A simplification of economic theory, it suggests that changes in the money supply do not influence real variables. This irrelevance of money for real variables is called monetary neutrality. Most economists believe that these classical ideas describe how the economy works in the long run.

The Model of Aggregate Supply and Aggregate Demand

This macroeconomic model allows us to examine how the aggregate price level and quantity of aggregate output are determined in the short run. It also provides a way to contrast how the economy behaves in the long run and how it behaves in the short run. Long Run Short run

Aggregate Demand Aggregate demand (AD) is the relationship between the quantity of output demanded and the aggregate price level. It tells us the quantity of goods and services people want to buy at any given level of prices. Recall the Quantity Theory of Money (MV=PY), where M is the money supply, V is the velocity of money, P is the price level, and Y is the amount of output. It makes the not quite realistic, but very convenient assumption that velocity is constant over time. Also, when interpreting this equation, recall that the quantity equation can be rewritten in terms of the supply and demand for real money balances: M/P = (M/P)d = kY, where k = 1/V is a parameter determining how much money people want to hold for every dollar of income. This equation states that supply of money balances M/P is equal to the demand and that demand is proportional to output. The assumption of constant velocity is equivalent to the assumption of a constant demand for real money balances per unit of output.

The Aggregate Demand Curve The Aggregate Demand (AD) curve shows the negative relationship between the price level P and quantity of goods and services demanded Y. It is drawn for a given value of the money supply M. The aggregate demand curve slopes downward: the higher the price level P, the lower the level of real balances M/P, and therefore the lower the quantity of goods and services demanded Y. As the price level decreases, we’d move down along the AD curve. Price level Any changes in M or V would shift the AD curve. Remember that the demand for real output varies inversely with the price level. AD Y = MV/P Output (Y)

Why the aggregate demand curve slopes downward Think about the supply and demand for real money balances. If output is higher, people engage in more transactions and need higher real balances M/P. For a fixed money supply M, higher real balances imply a lower price level. Conversely, if the price level is lower, real money balances are higher; the higher level of real balances allows a greater volume of transactions, which means a greater quantity of output is demanded.

More about the Aggregate Demand Curve The aggregate demand curve is drawn for a fixed value of the money supply. In other words, it tells us the possible combinations of P and Y for a given value of M. If the Fed changes the money supply, then the possible combinations of P and Y change, which means the aggregate demand curve shifts. Let’s see how.

Shifts in Aggregate Demand AD A decrease in the money supply M reduces the nominal value of output PY. For any given price level P, output Y is lower. Thus, a decrease in the money supply shifts the AD curve inward from AD to AD'. Price level Output (Y) AD'

Shifts in Aggregate Demand AD An increase in the money supply M raises the nominal value of output PY. For any given price level P, output Y is higher. Thus, an increase in the money supply shifts the AD curve outward from AD to AD'. Price level Output (Y) AD'

Aggregate Supply Aggregate supply (AS) is the relationship between the quantity of goods and services supplied and the price level. Because the firms that supply goods and services have flexible prices in the long run but sticky prices in the short run, the aggregate supply relationship depends on the time horizon. There are two different aggregate supply curves: the long-run aggregate supply curve (LRAS) and the short-run aggregate supply curve (SRAS). We also must discuss how the economy makes the transition from the short run to the long run. But, first, let’s build the long-run aggregate supply curve (LRAS).

The Vertical-Aggregate Supply Curve The Long Run: The Vertical-Aggregate Supply Curve Because the classical model describes how the economy behaves in the long run, we can derive the long-run aggregate supply curve from the classical model. Recall the amount of output produced depends on the fixed amounts of capital and labor and on the available technology. To show this, we write Y = F(K, L) = Y According the classical model, output does not depend on the price level. Let’s think about this considering the market clearing process in the labor market, the “L” component of the production function.

Market Clearing in the Labor Market Let’s begin at full employment, n*, with a wage of W/P0. Now let’s see how workers will respond when there is a sudden increase in the price level. At this new lower real wage, workers will cut back on hours worked. Real wage, W/P ns (Employees) But, at the same time, employers increase their demand for workers. n * W/P0 W/2P0 n n (Employers) nd What will happen next? Hours worked

Back to Equilibrium (n*) So, right now the labor market is in “disequilibrium” where the quantity demanded exceeds the quantity supplied. We’re now going to see how “flexible wages” will allow the labor market to come back to equilibrium, at full employment, n*. To hire more workers, the employer must raise the real wage to 2W. As a result of 2W, more workers are hired, and the labor market can move... W/P ns (Employees) Back to Equilibrium (n*) 2W/2P0 W/2P0 n n (Employers) nd n * Hours worked

The mechanism we just went through will enable us to build our long run aggregate supply curve. LRAS P The vertical line suggests that changes in the price level will have no lasting impact on full employment. Y Y Y=F (K, L)

The vertical-aggregate supply curve satisfies the classical dichotomy, because it implies that the level of output is independent of the money supply. This long-run level of output, Y, is called the full-employment or natural level of output. It is the level of output at which the economy’s resources are fully employed, or more realistically, at which unemployment is at its natural rate. LRAS P A reduction in the money supply shifts the aggregate demand curve downward from AD to AD'. Since the AS curve is vertical in the long run, the reduction in AD affects the price level, but not the level of output. A AD B AD' Y Y

The Short-Run: The Horizontal Aggregate Supply Curve Remember that the the vertical LRAS curve assumed that changes in the price level left no lasting impact on Y (because of the market-clearing process)--that will be the model for examining the long term. But we need a theory for the short run, defined as the interval of time during which markets are not fully cleared. LRAS A simple, but useful first approach is to assume short-run price rigidity meaning that the aggregate supply curve is flat. As AD shifts to AD we slide in an east-west direction to point B on the short run aggregate supply curve (SRAS). Then, in the long run, we move from B to C (move up and along AD). P C B P0 SRAS A AD AD Y Y Y = F (K,L)

The Long-run Equilibrium LRAS P SRAS AD Y Y Y = F (K,L) In the long run, the economy finds itself at the intersection of the long-run aggregate supply curve and aggregate demand curve. Because prices have adjusted to this level, the SRAS crosses this point as well.

A Reduction in Aggregate Demand LRAS P SRAS B A AD C AD' Y Y The economy begins in long-run equilibrium at point A. Then, a reduction in aggregate demand, perhaps caused by a decrease in the money supply M, moves the economy from point A to point B, where output is below its natural level. As prices fall, the economy recovers from the recession, moving from point B to point C.

Stabilization Policy Exogenous changes in aggregate supply or aggregate demand are called shocks. A shock that affects aggregate supply is called a supply shock. A shock that affects aggregate demand is called a demand shock. These shocks that disrupt the economy push output and unemployment away from their natural levels. A goal of the aggregate demand/aggregate supply model is to help explain how shocks cause economic fluctuations. Economists use the term stabilization policy to refer to the policy actions taken to reduce the severity of short-run economic fluctuations. Stabilization policy seeks to dampen the business cycle by keeping output and employment as close to their natural rate as possible. The model in this chapter is a simpler version of the one we’ll see in coming chapters.

Shocks to Aggregate Demand LRAS P C SRAS B A AD' AD Y Y The economy begins in long-run equilibrium at point A. An increase in aggregate demand, due to an increase in the velocity of money, moves the economy from point A to point B, where output is above its natural level. As prices rise, output gradually returns to its natural rate, and the economy moves from point B to point C.

Shocks to Aggregate Supply LRAS P B SRAS' SRAS A AD Y Y An adverse supply shock pushes up costs and prices. If AD is held constant, the economy moves from point A to point B, leading to stagflation—a combination of increasing prices and declining level of output. Eventually, as prices fall, the economy returns to the natural rate at point A.

Accommodating an Adverse Supply Shock LRAS P B SRAS' SRAS A AD' AD Y Y In response to an adverse supply shock, the Fed can increase aggregate demand to prevent a reduction in output. The economy moves from point A to point B. The cost of this policy is a permanently higher level of prices.

Key Concepts of Chapter 9 Aggregate demand Aggregate supply Shocks Demand shocks Supply shocks Stabilization policy