Worth: Mankiw Economics 5e User JoENA: Job EFFo1419: 6264_ ch03: Pg 40: 23909 #/ eps at 1004 ml ed,Feb13,20028:554M
User JOEWA:Job EFF01419:6264_ch03:Pg 40:23909#/eps at 100% *23909* Wed, Feb 13, 2002 8:55 AM
Worth: Mankiw Economics 5e ort l Classical Theory: The Economy in the Long Run User JOENA: Job EFF01419: 6264_ch03: Pg 41: 24836#/eps at 1009 Il Wea,Feb13,20028:55
User JOEWA:Job EFF01419:6264_ch03:Pg 41:24836#/eps at 100% *24836* Wed, Feb 13, 2002 8:55 AM part II Classical Theory: The Economy in the Long Run
Worth: Mankiw Economics 5e CHAPTER THREE National Income: Where t comes From and where丨 t Goes A large income is the best recipe for happiness I ever heard of. Jane Austen The most important macroeconomic variable is gross domestic product(GDP) As we have seen, GDP measures both a nations total output of goods and ser- vices and its total income. To appreciate the significance of GDP, one need only take a quick look at international data: compared with their poorer counterparts, nations with a high level of gDP per person have everything from better child- hood nutrition to more televisions per household. A large GDP does not ensure that all of a nations citizens are happy, but it may be the best recipe for happiness hat macroeconomists have to offer This chapter addresses four groups of questions about the sources and uses of a nation s gdp. How much do the firms in the economy produce? What determines a na- tion,'s total income? Who gets the income from production? How much goes to compensate workers, and how much goes to compensate owners of capital? for investment, and how much does the government buy for pubic o a Who buys the output of the economy? How much do households pr hase for consumption, how much do households and firms purchas What equilibrates the demand for and supply of goods and services? What ensures that desired spending on consumption, investment, and gover ment purchases equals the level of production? To answer these questions, we must examine how the various parts of the econ- omy interact. a good place to start is the circular flow diagram. In Chapter 2 we traced the circular flow of dollars in a hypothetical economy that produced one product, bread, from labor services. Figure 3-1 more accurately reflects how real economies function. It shows the linkages among the economic actors--households, firms, User JOENA: Job EFF01419: 6264_ch03: Pg 42: 24837 #/eps at 1009 I ed,Feb13,20028:554M
User JOEWA:Job EFF01419:6264_ch03:Pg 42:24837#/eps at 100% *24837* Wed, Feb 13, 2002 8:55 AM The most important macroeconomic variable is gross domestic product (GDP). As we have seen, GDP measures both a nation’s total output of goods and services and its total income.To appreciate the significance of GDP, one need only take a quick look at international data: compared with their poorer counterparts, nations with a high level of GDP per person have everything from better childhood nutrition to more televisions per household.A large GDP does not ensure that all of a nation’s citizens are happy, but it may be the best recipe for happiness that macroeconomists have to offer. This chapter addresses four groups of questions about the sources and uses of a nation’s GDP: ➤ How much do the firms in the economy produce? What determines a nation’s total income? ➤ Who gets the income from production? How much goes to compensate workers, and how much goes to compensate owners of capital? ➤ Who buys the output of the economy? How much do households purchase for consumption, how much do households and firms purchase for investment, and how much does the government buy for public purposes? ➤ What equilibrates the demand for and supply of goods and services? What ensures that desired spending on consumption, investment, and government purchases equals the level of production? To answer these questions, we must examine how the various parts of the economy interact. A good place to start is the circular flow diagram. In Chapter 2 we traced the circular flow of dollars in a hypothetical economy that produced one product, bread,from labor services.Figure 3-1 more accurately reflects how real economies function. It shows the linkages among the economic actors—households, firms, National Income: Where It Comes From and Where It Goes 3CHAPTER A large income is the best recipe for happiness I ever heard of. — Jane Austen THREE 42 |
Worth: Mankiw Economics 5e CHAPTER 3 National Income: Where It Comes From and Where It Goes 43 figure 3-1 ncome Markets for Factors Facto of Production Private saving Markets Public aving Taxes Government Firms Government Consumpti Markets Firm revenue Goods and Services The Circular Flow of Dollars Through the Economy This figure is a more realistic version of the circular flow diagram found in Chapter 2. Each yellow box represents an economic actor-households, firms, and the government. Each blue box represents a type of market-the markets for goods and services, the markets for the factors of production, and financial markets. The green arrows show the flow of dollars among the economic actors through the three types of markets. and the government-and how dollars fow among them through the various markets in the economy. Let's look at the flow of dollars from the viewpoints of these economic ac- tors Households receive income and use it to pay taxes to the government, to consume goods and services, and to save through the financial markets Firms receive revenue from the sale of goods and services and use it to pay for the factors of production. Both households and firms borrow in financial markets to buy investment goods, such as houses and factories. The govern ment receives revenue from taxes and uses it to pay for government pur- chases. Any excess of tax revenue over government spending is called public aving, which can be either positive (a budget surplus) or negative(a budget deficit) In this chapter we develop a basic classical model to explain the economic interactions depicted in Figure 3-1. We begin with firms and look at what User JoENA: Job EFFo1419: 6264_ch03: Pg 43: 24979 #/eps at 1004 ml ed,Feb13,20028:554M
User JOEWA:Job EFF01419:6264_ch03:Pg 43:24979#/eps at 100% *24979* Wed, Feb 13, 2002 8:55 AM and the government—and how dollars flow among them through the various markets in the economy. Let’s look at the flow of dollars from the viewpoints of these economic actors. Households receive income and use it to pay taxes to the government, to consume goods and services, and to save through the financial markets. Firms receive revenue from the sale of goods and services and use it to pay for the factors of production. Both households and firms borrow in financial markets to buy investment goods, such as houses and factories.The government receives revenue from taxes and uses it to pay for government purchases. Any excess of tax revenue over government spending is called public saving, which can be either positive (a budget surplus) or negative (a budget deficit). In this chapter we develop a basic classical model to explain the economic interactions depicted in Figure 3-1. We begin with firms and look at what CHAPTER 3 National Income: Where It Comes From and Where It Goes | 43 figure 3-1 Income Private saving Taxes Consumption Firm revenue Investment Public saving Government purchases Factor payments Markets for Factors of Production Markets for Goods and Services Financial Markets Households Government Firms The Circular Flow of Dollars Through the Economy This figure is a more realistic version of the circular flow diagram found in Chapter 2. Each yellow box represents an economic actor—households, firms, and the government. Each blue box represents a type of market—the markets for goods and services, the markets for the factors of production, and financial markets. The green arrows show the flow of dollars among the economic actors through the three types of markets
Worth: Mankiw Economics 5e 44 PART 11 Classical Theory: The Economy in the Long Run determines their level of production(and, thus, the level of national income) Then we examine how the markets for the factors of production distribute this income to households. Next. we consider how much of this income households consume and how much they save. In addition to discussing the demand for goods and services arising from the consumption of households, we discuss the demand arising from investment and government purchases Finally, we come full circle and examine how the demand for goods and ser- vices(the sum of consumption, investment, and government purchases)and the supply of goods and services(the level of production)are brought into balance 3-1 What Determines the Total Production of Goods and services? An economys output of goods and services--its GDP-depends on(1)its tity of inputs, called the factors of production, and(2) its ability to turn nto output, as represented by the production function. We discuss each of In tur The Factors of production Factors of production are the inputs used to produce goods and services.The mportant factors of production are capital and labor. Capital is the set of tools that workers use. the construction worker's crane the accountant's calcu- lator, and this author's personal computer. Labor is the time people spend work ing. We use the symbol K to denote the amount of capital and the symbol Lto In this chapter we take the economy's factors of production as given. In other words, we assume that the economy has a fixed amount of capital and a fixed amount of labor. We write L The overbar means that each variable is fixed at some level. In Chapter 7 we ex amine what happens when the factors of production change over time, as they do in the real world. For now, to keep our analysis simple, we assume fixed amounts of capital and labor. We also assume here that the factors of production are fully utilized-that is, that no resources are wasted. Again, in the real world, part of the labor force is unemployed, and some capital lies idle. In Chapter 6 we examine the rea- sons for unemployment, but for now we assume that capital and labor are fully em User JOENA: Job EFF01419: 6264_ch03: Pg 44: 24980#/eps at 1009 IllI ed,Feb13,20028:554M
User JOEWA:Job EFF01419:6264_ch03:Pg 44:24980#/eps at 100% *24980* Wed, Feb 13, 2002 8:55 AM determines their level of production (and, thus, the level of national income). Then we examine how the markets for the factors of production distribute this income to households. Next, we consider how much of this income households consume and how much they save. In addition to discussing the demand for goods and services arising from the consumption of households, we discuss the demand arising from investment and government purchases. Finally, we come full circle and examine how the demand for goods and services (the sum of consumption, investment, and government purchases) and the supply of goods and services (the level of production) are brought into balance. 3-1 What Determines the Total Production of Goods and Services? An economy’s output of goods and services—its GDP—depends on (1) its quantity of inputs, called the factors of production, and (2) its ability to turn inputs into output, as represented by the production function.We discuss each of these in turn. The Factors of Production Factors of production are the inputs used to produce goods and services.The two most important factors of production are capital and labor. Capital is the set of tools that workers use: the construction worker’s crane, the accountant’s calculator, and this author’s personal computer. Labor is the time people spend working.We use the symbol K to denote the amount of capital and the symbol L to denote the amount of labor. In this chapter we take the economy’s factors of production as given. In other words, we assume that the economy has a fixed amount of capital and a fixed amount of labor.We write K = K _ . L = L _ . The overbar means that each variable is fixed at some level. In Chapter 7 we examine what happens when the factors of production change over time, as they do in the real world. For now, to keep our analysis simple, we assume fixed amounts of capital and labor. We also assume here that the factors of production are fully utilized—that is, that no resources are wasted.Again, in the real world, part of the labor force is unemployed, and some capital lies idle. In Chapter 6 we examine the reasons for unemployment, but for now we assume that capital and labor are fully employed. 44 | PART II Classical Theory: The Economy in the Long Run
Worth: Mankiw Economics 5e CHAPTER 3 National Income: Where It Comes From and Where It Goes 45 The Production Function The available production technology determines how much output is produced from given amounts of capital and labor. Economists express the available tech- nology using a production function. Letting Y denote the amount of output we write the production function as Y=FK, L) This equation states that output is a function of the amount of capital and the amount of labor The production function reflects the available technology for turning capital and labor into output. If someone invents a better way to produce a good, the re- sult is more output from the same amounts of capital and labor. Thus, technolog ical change alters the production function Many production functions have a property called constant returns to scale. a production function has constant returns to scale if an increase of an equal percentage in all factors of production causes an increase in output of the same percentage. If the production function has constant returns to scale, then percent. Mathematically, a production function has constant returns to scaler o e get 10 percent more output when we increase both capital and labor by zY= F(2K, 2L) for any positive number z. This equation says that if we multiply both the amount of capital and the amount of labor by some number z, output is also multiplied by z In the next section we see that the assumption of constant returns to scale has an important implication for how the income from production is distributed. As an example of a production function, consider production at a bakery. The kitchen and its equipment are the bakery's capital, the workers hired to make the bread are its labor, and the loaves of bread are its output. The bakery's production function shows that the number of loaves produced depends on the amount of equipment and the number of workers. If the production function has constant returns to scale, then doubling the amount of equipment and the number of workers doubles the amount of bread produced The Supply of Goods and Services We can now see that the factors of production and the production function to- gether determine the quantity of goods and services supplied, which in turn equals the economy's output. To express this mathematically, we write Y=F(K, L) In this chapter, because we assume that the supplies of capital and labor and the technology are fixed, output is also fixed (at a level denoted here as Y). When we User JOENA: Job EFF01419: 6264_ch03: Pg 45: 24981 #/eps at 1009 I ed,Feb13,20028:554M
User JOEWA:Job EFF01419:6264_ch03:Pg 45:24981#/eps at 100% *24981* Wed, Feb 13, 2002 8:55 AM The Production Function The available production technology determines how much output is produced from given amounts of capital and labor. Economists express the available technology using a production function. Letting Y denote the amount of output, we write the production function as Y = F(K, L). This equation states that output is a function of the amount of capital and the amount of labor. The production function reflects the available technology for turning capital and labor into output. If someone invents a better way to produce a good, the result is more output from the same amounts of capital and labor.Thus, technological change alters the production function. Many production functions have a property called constant returns to scale. A production function has constant returns to scale if an increase of an equal percentage in all factors of production causes an increase in output of the same percentage. If the production function has constant returns to scale, then we get 10 percent more output when we increase both capital and labor by 10 percent. Mathematically, a production function has constant returns to scale if zY = F(zK, zL) for any positive number z.This equation says that if we multiply both the amount of capital and the amount of labor by some number z, output is also multiplied by z. In the next section we see that the assumption of constant returns to scale has an important implication for how the income from production is distributed. As an example of a production function, consider production at a bakery.The kitchen and its equipment are the bakery’s capital, the workers hired to make the bread are its labor, and the loaves of bread are its output.The bakery’s production function shows that the number of loaves produced depends on the amount of equipment and the number of workers. If the production function has constant returns to scale, then doubling the amount of equipment and the number of workers doubles the amount of bread produced. The Supply of Goods and Services We can now see that the factors of production and the production function together determine the quantity of goods and services supplied, which in turn equals the economy’s output.To express this mathematically, we write Y = F(K _ , L _ ) = Y _ . In this chapter, because we assume that the supplies of capital and labor and the technology are fixed, output is also fixed (at a level denoted here as Y –).When we CHAPTER 3 National Income: Where It Comes From and Where It Goes | 45
Worth: Mankiw Economics 5e 46 PART 11 Classical Theory: The Economy in the Long Ru discuss economic growth in Chapters 7 and 8, we will examine how increases in capital and labor and improvements in the production technology lead to growth in the economys or 3-2 How Is National Income distributed to the Factors of production? As we discussed in Chapter 2, the total output of an economy equals its total in- come. Because the factors of production and the production function together determine the total output of goods and services, they also determine national income. The circular flow diagram in Figure 3-1 shows that this national in- come flows from firms to households through the markets for the factors of In this section we continue developing our model of the economy by dis- cussing how these factor markets work. Economists have long studied factor markets to understand the distribution of income.(For example, Karl Marx, the noted nineteenth-century economist, spent much time trying to explain the in- comes of capital and labor. The political philosophy of communism was in part based on Marx's now-discredited theory. Here we examine the modern theory of how national income is divided among the factors of production. This theory, called the neoclassical theory of distribution, is accepted by most economists today. Factor Prices The distribution of national income is determined by factor prices. Factor prices are the amounts paid to the factors of production-the wage workers earn and the rent the owners of capital collect. As Figure 3-2 illustrates, the price each factor of production receives for its services is in turn determined by the supply and demand for that factor. Because we have assumed that the economy's factors of production are fixed, the factor supply curve in Figure 3-2 is vertical. The intersection of the downward-sloping factor demand curve and the vertical supply curve determines the equilibrium factor price To understand factor prices and the distribution of income, we must examine the demand for the factors of production. Because factor demand arises from the housands of firms that use capital and labor, we now look at the decisions faced by a typical firm about how much of these factors to employ. The Decisions Facing the Competitive Firm The simplest assumption to make about a typical firm is that it is competitive A competitive firm is small relative to the markets in which it trades, so it has little influence on market prices. For example, our firm produces a good and sells it at the market price. Because many firms produce this good, our firm can sell as User JOENA: Job EFF01419: 6264_ch03: Pg 46: 24982#/eps at 1009 II ed,Feb13,20028:554M
User JOEWA:Job EFF01419:6264_ch03:Pg 46:24982#/eps at 100% *24982* Wed, Feb 13, 2002 8:55 AM discuss economic growth in Chapters 7 and 8, we will examine how increases in capital and labor and improvements in the production technology lead to growth in the economy’s output. 3-2 How Is National Income Distributed to the Factors of Production? As we discussed in Chapter 2, the total output of an economy equals its total income. Because the factors of production and the production function together determine the total output of goods and services, they also determine national income. The circular flow diagram in Figure 3-1 shows that this national income flows from firms to households through the markets for the factors of production. In this section we continue developing our model of the economy by discussing how these factor markets work. Economists have long studied factor markets to understand the distribution of income. (For example, Karl Marx, the noted nineteenth-century economist, spent much time trying to explain the incomes of capital and labor.The political philosophy of communism was in part based on Marx’s now-discredited theory.) Here we examine the modern theory of how national income is divided among the factors of production.This theory, called the neoclassical theory of distribution, is accepted by most economists today. Factor Prices The distribution of national income is determined by factor prices. Factor prices are the amounts paid to the factors of production—the wage workers earn and the rent the owners of capital collect. As Figure 3-2 illustrates, the price each factor of production receives for its services is in turn determined by the supply and demand for that factor. Because we have assumed that the economy’s factors of production are fixed, the factor supply curve in Figure 3-2 is vertical. The intersection of the downward-sloping factor demand curve and the vertical supply curve determines the equilibrium factor price. To understand factor prices and the distribution of income, we must examine the demand for the factors of production. Because factor demand arises from the thousands of firms that use capital and labor, we now look at the decisions faced by a typical firm about how much of these factors to employ. The Decisions Facing the Competitive Firm The simplest assumption to make about a typical firm is that it is competitive. A competitive firm is small relative to the markets in which it trades, so it has little influence on market prices. For example, our firm produces a good and sells it at the market price. Because many firms produce this good, our firm can sell as 46 | PART II Classical Theory: The Economy in the Long Run
Worth: Mankiw Ecol CHAPTER 3 National Income: Where It Comes From and Where It Goes 47 Factor price How a Factor of production is to any factor of production supply mand for that factors services Because we have assumed that supply is fixed, the supply curve is vertical. The demand curve downward sloping. The factor price Quantity of factor much as it wants without causing the price of the good to fall, or it can stop sell ing altogether without causing the price of the good to rise. Similarly, our firm cannot influence the wages of the workers it employs because many other local firms also employ workers. The firm has no reason to pay more than the market wage, and if it tried to pay less, its workers would take jobs elsewhere. Therefore, the competitive firm takes the prices of its output and its inputs as giver To make its product, the firm needs two factors of production, capital and labor. As we did for the aggregate economy, we represent the firms production technology by the production function =F(K, L) where Y is the number of units produced (the firms output), K the number of machines used(the amount of capital), and L the number of hours worked by the firms employees(the amount of labor). The firm produces more output if it has more machines or if its employees work more hours The firm sells its output at a price P, hires workers at a wage w, and rents cap ital at a rate R. Notice that when we speak of firms renting capital, we are assum- ing that households own the economy's stock of capital. In this analysis, households rent out their capital, just as they sell their labor. The firm obtains both factors of production from the households that own them. I The goal of the firm is to maximize profit. Profit is revenue minus costs--it is what the owners of the firm keep after paying for the costs of production. Rev- enue equals Px Y, the selling price of the good P multiplied by the amount of I This is a simplification In the real world, the ownership of capital is indirect because firms own apital and households own the firms. That is, real firms have two functions: owning capital and producing output. To help us understand how the factors of production are compensated, however, we assume that firms only produce output and that households own capital directly. User JOENA: Job EFF01419: 6264_ch03: Pg 47: 24983#/eps at 1009 Il wed,Feb13,20028:564M
User JOEWA:Job EFF01419:6264_ch03:Pg 47:24983#/eps at 100% *24983* Wed, Feb 13, 2002 8:56 AM much as it wants without causing the price of the good to fall, or it can stop selling altogether without causing the price of the good to rise. Similarly, our firm cannot influence the wages of the workers it employs because many other local firms also employ workers.The firm has no reason to pay more than the market wage, and if it tried to pay less, its workers would take jobs elsewhere.Therefore, the competitive firm takes the prices of its output and its inputs as given. To make its product, the firm needs two factors of production, capital and labor. As we did for the aggregate economy, we represent the firm’s production technology by the production function Y = F(K, L), where Y is the number of units produced (the firm’s output), K the number of machines used (the amount of capital), and L the number of hours worked by the firm’s employees (the amount of labor).The firm produces more output if it has more machines or if its employees work more hours. The firm sells its output at a price P, hires workers at a wage W, and rents capital at a rate R. Notice that when we speak of firms renting capital, we are assuming that households own the economy’s stock of capital. In this analysis, households rent out their capital, just as they sell their labor. The firm obtains both factors of production from the households that own them.1 The goal of the firm is to maximize profit. Profit is revenue minus costs—it is what the owners of the firm keep after paying for the costs of production. Revenue equals P × Y, the selling price of the good P multiplied by the amount of CHAPTER 3 National Income: Where It Comes From and Where It Goes | 47 figure 3-2 Equilibrium factor price Factor supply Factor demand Quantity of factor Factor price How a Factor of Production Is Compensated The price paid to any factor of production depends on the supply and demand for that factor’s services. Because we have assumed that supply is fixed, the supply curve is vertical. The demand curve is downward sloping. The intersection of supply and demand determines the equilibrium factor price. 1This is a simplification. In the real world, the ownership of capital is indirect because firms own capital and households own the firms.That is, real firms have two functions: owning capital and producing output.To help us understand how the factors of production are compensated, however, we assume that firms only produce output and that households own capital directly
Worth: Mankiw Economics 5e 48 PART 11 Classical Theory: The Economy in the Long Ru che good the firm produces Y Costs include both labor costs and capital costs. Labor costs equal WX L, the wage W times the amount of labor L Capital costs equal r x K, the rental price of capital R times the amount of capital K. We can Profit= Revenue- Labor Costs-Capital Costs WL RK To see how profit depends on the factors of production, we use the production function Y= F(K, L)to substitute for Y to obtain Profit= PF(K, L)-WL-RK This equation shows that profit depends on the product price P, the factor prices W and R, and the factor quantities L and K. The competitive firm takes the product price and the factor prices as given and chooses the amounts of labor and capital that maximize profit The Firm's Demand for Factors We now know that our firm will hire labor and rent capital in the quantities that maximize profit. But what are those profit-maximizing quantities? To answer this question, we first consider the quantity of labor and then the quantity of capital The Marginal Product of Labor The more labor the firm employs, the more output it produces. The marginal product of labor(MPL) is the extra amount of output the firm gets from one extra unit of labor, holding the amount of capital fixed. We can express this using the production function MPL= F(K, L+1)-F(K, L) m first term on the right-hand side is the amount of output produced with K of capital and L+ 1 units of labor; the second term is the amount of output oduced with K units of capital and L units of labor. This equation states that the marginal product of labor is the difference between the amount of output produced with L+ 1 units of labor and the amount produced with only L units of labor Most production functions have the property of diminishing marginal product: holding the amount of capital fixed, the marginal product of labor de creases as the amount of labor increases. Consider again the production of bread at a bakery. As a bakery hires more labor, it produces more bread. The MPL is the amount of extra bread produced when an extra unit of labor is hired. As more labor is added to a fixed amount of capital, however, the MPL falls. Fewer addi- tional loaves are produced because workers are less productive when the kitchen is more crowded. In other words, holding the size of the kitchen fixed, each ad ditional worker adds fewer loaves of bread to the bakery's output Figure 3-3 graphs the production function. It illustrates what happens to the amount of output when we hold the amount of capital constant and vary the User JoENA: Job EFFo1419: 6264_ch03: Pg 48: 24984#/eps at 1004 mI wed,Feb13,20028:564M
User JOEWA:Job EFF01419:6264_ch03:Pg 48:24984#/eps at 100% *24984* Wed, Feb 13, 2002 8:56 AM the good the firm produces Y. Costs include both labor costs and capital costs. Labor costs equal W × L, the wage W times the amount of labor L. Capital costs equal R × K, the rental price of capital R times the amount of capital K.We can write Profit = Revenue − Labor Costs − Capital Costs = PY − WL − RK. To see how profit depends on the factors of production, we use the production function Y = F(K, L) to substitute for Y to obtain Profit = PF(K, L) − WL − RK. This equation shows that profit depends on the product price P, the factor prices W and R, and the factor quantities L and K. The competitive firm takes the product price and the factor prices as given and chooses the amounts of labor and capital that maximize profit. The Firm’s Demand for Factors We now know that our firm will hire labor and rent capital in the quantities that maximize profit. But what are those profit-maximizing quantities? To answer this question, we first consider the quantity of labor and then the quantity of capital. The Marginal Product of Labor The more labor the firm employs, the more output it produces. The marginal product of labor (MPL) is the extra amount of output the firm gets from one extra unit of labor, holding the amount of capital fixed.We can express this using the production function: MPL = F(K, L + 1) − F(K, L). The first term on the right-hand side is the amount of output produced with K units of capital and L + 1 units of labor; the second term is the amount of output produced with K units of capital and L units of labor.This equation states that the marginal product of labor is the difference between the amount of output produced with L + 1 units of labor and the amount produced with only L units of labor. Most production functions have the property of diminishing marginal product: holding the amount of capital fixed, the marginal product of labor decreases as the amount of labor increases. Consider again the production of bread at a bakery. As a bakery hires more labor, it produces more bread.The MPL is the amount of extra bread produced when an extra unit of labor is hired. As more labor is added to a fixed amount of capital, however, the MPL falls. Fewer additional loaves are produced because workers are less productive when the kitchen is more crowded. In other words, holding the size of the kitchen fixed, each additional worker adds fewer loaves of bread to the bakery’s output. Figure 3-3 graphs the production function. It illustrates what happens to the amount of output when we hold the amount of capital constant and vary the 48 | PART II Classical Theory: The Economy in the Long Run
Worth: Mankiw Economics 5e CHAPTER 3 National Income: Where It Comes From and Where It Goes 49 figure 3-3 RK, L) 2. As more MPL 1. The slope of MPL function equals The Production Function This curve shows how output depends on labor input, holding the amount of capital constant. The marginal product of labor MPL is the change in output when the labor input is increased by 1 unit. As the amount of labor increases, the production function becomes flatter, indicating diminishing marginal product. amount of labor. This figure shows that the marginal product of labor is the slope of the production function. As the amount of labor increases, the production function becomes fatter, indicating diminishing marginal product From the Marginal Product of Labor to Labor Demand When the compe titive, profit-maximizing firm is deciding whether to hire an additional unit of labor, it considers how that decision would affect profits. It therefore compares the extra revenue from the increased production that results from the added labor to the extra cost of higher spending on wages. The increase in revenue from an addi- onal unit of labor depends on two variables: the marginal product of labor and the price of the output. Because an extra unit of labor produces MPL units of output and each unit of output sells for P dollars, the extra revenue is P X MPL. The extra cost of hiring one more unit of labor is the wage w. Thus, the change in profit from hiring an additional unit of labor is △ Profit=△ Revenue-△Cost =(P×MPL)-W The symbol A(called delta) denotes the change in a variable User JOENA: Job EFF01419: 6264_ch03: Pg 49: 24985#/eps at 1009 II wed,Feb13,20028:564M
User JOEWA:Job EFF01419:6264_ch03:Pg 49:24985#/eps at 100% *24985* Wed, Feb 13, 2002 8:56 AM amount of labor.This figure shows that the marginal product of labor is the slope of the production function. As the amount of labor increases, the production function becomes flatter, indicating diminishing marginal product. From the Marginal Product of Labor to Labor Demand When the competitive, profit-maximizing firm is deciding whether to hire an additional unit of labor,it considers how that decision would affect profits.It therefore compares the extra revenue from the increased production that results from the added labor to the extra cost of higher spending on wages.The increase in revenue from an additional unit of labor depends on two variables: the marginal product of labor and the price of the output. Because an extra unit of labor produces MPL units of output and each unit of output sells for P dollars, the extra revenue is P × MPL. The extra cost of hiring one more unit of labor is the wage W.Thus, the change in profit from hiring an additional unit of labor is D Profit = DRevenue − DCost = (P × MPL) − W. The symbol D (called delta) denotes the change in a variable. CHAPTER 3 National Income: Where It Comes From and Where It Goes | 49 figure 3-3 F(K, L) Output, Y Labor, L MPL 1 MPL 1 MPL 1 1. The slope of production function equals marginal product of labor. 2. As more labor is added, the marginal product of labor declines. The Production Function This curve shows how output depends on labor input, holding the amount of capital constant. The marginal product of labor MPL is the change in output when the labor input is increased by 1 unit. As the amount of labor increases, the production function becomes flatter, indicating diminishing marginal product
