1นโยบายการคลังกับการขยายตัวเศรษฐกิจ: การสะสมทุน (Capital Accumulation) This lecture drawn heavily from Mankiw, Macroeconomics, 5th edition, 2003
2เสถียรภาพกับการขยายตัวเศรษฐกิจ นโยบายการคลังเพื่อการรักษาเสถียรภาพมักหมายถึงการลดการขาดดุลการคลังซึ่งการบริหารนโยบายดังกล่าวมักต้องมีต้นทุนในรูปของโอกาสการขยายตัวในระยะยาว (เพราะต้องเสียทรัพยากรในการรักษาเสถียรภาพของระบบเศรษฐกิจ เช่นการลดการใช้จ่ายเป็นต้น)ดังนั้นในการออกแบบนโยบายการรักษาเสถียรภาพจึงต้องคำนึงถึงการขยายตัวของเศรษฐกิจด้วยตัวอย่าง: public capital declined suggest lower of economic investment.การรักษาเสถียรภาพกับการขยายตัวเศรษฐกิจต้องการการจัดการด้านอุปสงค์ที่มุ่งเพื่อส่งเสริมการเพิ่มของStabilization and growth requires that demand management policies be complemented by policies aimed at increasing potential output.
9Why Productivity Is So Important To understand the large differences in living standards across countries, we must focus on the production of goods and services.
10การจำแนกและกำหนดผลิตภัณฑ์การผลิต The inputs used to produce goods and services are called the factors of production.The factors of production directly determine productivity.
11ผลิตภัณฑ์ภาคการผลิต The Factors of Production Physical capital Human capitalNatural resourcesTechnological knowledge
12ผลิตภัณฑ์ภาคการผลิต Physical Capital is a produced factor of production.It is an input into the production process that in the past was an output from the production process.is the stock of equipment and structures that are used to produce goods and services.Tools used to build or repair automobiles.Tools used to build furniture.Office buildings, schools, etc.
13ผลิตภัณฑ์ภาคการผลิต Human Capital the economist’s term for the knowledge and skills that workers acquire through education, training, and experienceLike physical capital, human capital raises a nation’s ability to produce goods and services.
14ผลิตภัณฑ์ภาคการผลิต Natural Resources inputs used in production that are provided by nature, such as land, rivers, and mineral deposits.Renewable resources include trees and forests.Nonrenewable resources include petroleum and coal.can be important but are not necessary for an economy to be highly productive in producing goods and services.
15ผลิตภัณฑ์ภาคการผลิต Technological Knowledge society’s understanding of the best ways to produce goods and services.Human capital refers to the resources expended transmitting this understanding to the labor force.
16FYI: The Production Function Economists often use a production function to describe the relationship between the quantity of inputs used in production and the quantity of output from production.
17FYI: The Production Function Y = A F(L, K, H, N)Y = quantity of outputA = available production technologyL = quantity of laborK = quantity of physical capitalH = quantity of human capitalN = quantity of natural resourcesF( ) is a function that shows how the inputs are combined.
18FYI: The Production Function A production function has constant returns to scale if, for any positive number x,xY = A F(xL, xK, xH, xN)That is, a doubling of all inputs causes the amount of output to double as well.
19FYI: The Production Function Production functions with constant returns to scale have an interesting implication.Setting x = 1/L,Y/ L = A F(1, K/ L, H/ L, N/ L)Where:Y/L = output per workerK/L = physical capital per workerH/L = human capital per workerN/L = natural resources per worker
20FYI: The Production Function The preceding equation says that productivity (Y/L) depends on physical capital per worker (K/L), human capital per worker (H/L), and natural resources per worker (N/L), as well as the state of technology, (A).
21The production function In aggregate terms: Y = F (K, L)Define: y = Y/L = output per workerk = K/L = capital per workerAssume constant returns to scale: zY = F (zK, zL ) for any z > 0Pick z = 1/L. ThenY/L = F (K/L, 1)y = F (k, 1)y = f(k) where f(k) = F(k, 1)
22The production function Output per worker, yCapital per worker, kf(k)1MPK = f(k +1) – f(k)Note: this production function exhibits diminishing MPK.
23The national income identity Y = C + I (remember, no G )In “per worker” terms: y = c + i where c = C/L and i = I /L
24The consumption function s = the saving rate, the fraction of income that is saved(s is an exogenous parameter)Note: s is the only lowercase variable that is not equal to its uppercase version divided by LConsumption function: c = (1–s)y (per worker)
25Saving and investment saving (per worker) = y – c = y – (1–s)y = sy National income identity is y = c + iRearrange to get: i = y – c = sy (investment = saving)Using the results above, i = sy = sf(k)
26Output, consumption, and investment Output per worker, yCapital per worker, kf(k)y1k1c1sf(k)i1
27Depreciation = the rate of depreciation = the fraction of the capital stock that wears out each periodDepreciation per worker, kCapital per worker, kk1
28Capital accumulation k = s f(k) – k The basic idea: Investment increases the capital stock, depreciation reduces it.Change in capital stock = investment – depreciationk = i – kSince i = sf(k) , this becomes:k = s f(k) – k
29The equation of motion for k k = s f(k) – kThe Solow model’s central equationDetermines behavior of capital over time……which, in turn, determines behavior of all of the other endogenous variables because they all depend on k. E.g.,income per person: y = f(k)consumption per person: c = (1–s) f(k)
30การขยายตัวเศรษฐกิจกับนโยบายรัฐ ECONOMIC GROWTH AND PUBLIC POLICY รัฐบาลสามารถออกแบบนโยบายที่จะเป็นการเพิ่มผลิตภาพ (productivity) และคุณภาพชีวิต (living standards) ของประชาชนได้อยู่ตลอดเวลา
31การขยายตัวเศรษฐกิจกับนโยบายรัฐ Government Policies That Raise Productivity and Living StandardsEncourage saving and investment.Encourage investment from abroadEncourage education and training.Establish secure property rights and maintain political stability.Promote free trade.Promote research and development.
32The steady state k = s f(k) – k If investment is just enough to cover depreciation [sf(k) = k ],then capital per worker will remain constant: k = 0.This occurs at one value of k, denoted k*, called the steady state capital stock.
33An increase in the saving rate An increase in the saving rate raises investment……causing k to grow toward a new steady state:Investment and depreciationkks2 f(k)s1 f(k)
34Prediction: Higher s higher k*. And since y = f(k) , higher k* higher y* .Thus, the Solow model predicts that countries with higher rates of saving and investment will have higher levels of capital and income per worker in the long run.
35International evidence on investment rates and income per person 100,000Income perperson in2000(log scale)10,0001,000Figure 7-6, p Source: Penn World Table version 6.1.1005101520253035Investment as percentage of output
36The Golden Rule: Introduction Different values of s lead to different steady states. How do we know which is the “best” steady state?The “best” steady state has the highest possible consumption per person: c* = (1–s) f(k*).An increase in sleads to higher k* and y*, which raises c*reduces consumption’s share of income (1–s), which lowers c*.So, how do we find the s and k* that maximize c*?
37The Golden Rule capital stock the Golden Rule level of capital, the steady state value of k that maximizes consumption.To find it, first express c* in terms of k*:c* = y* i*= f (k*) i*= f (k*) k*In the steady state: i* = k* because k = 0.
38The Golden Rule capital stock steady state output and depreciationsteady-state capital per worker, k* k*Then, graph f(k*) and k*, look for the point where the gap between them is biggest.f(k*)
39The Golden Rule capital stock c* = f(k*) k* is biggest where the slope of the production function equals the slope of the depreciation line: k*f(k*)MPK = steady-state capital per worker, k*
40The transition to the Golden Rule steady state The economy does NOT have a tendency to move toward the Golden Rule steady state.Achieving the Golden Rule requires that policymakers adjust s.This adjustment leads to a new steady state with higher consumption.But what happens to consumption during the transition to the Golden Rule?
41Starting with too much capital then increasing c* requires a fall in s.In the transition to the Golden Rule, consumption is higher at all points in time.timeycit0
42Starting with too little capital then increasing c* requires an increase in s.Future generations enjoy higher consumption, but the current one experiences an initial drop in consumption.ycit0time
43Population growthAssume that the population (and labor force) grow at rate n. (n is exogenous.)EX: Suppose L = 1,000 in year 1 and the population is growing at 2% per year (n = 0.02).Then L = n L = 0.02 1,000 = 20, so L = 1,020 in year 2.
44Break-even investment ( + n)k = break-even investment, the amount of investment necessary to keep k constant.Break-even investment includes: k to replace capital as it wears outn k to equip new workers with capital(Otherwise, k would fall as the existing capital stock would be spread more thinly over a larger population of workers.)
45The equation of motion for k With population growth, the equation of motion for k isk = s f(k) ( + n) kactual investmentbreak-even investment
46The Solow model diagram k = s f(k) ( +n)kInvestment, break-even investmentCapital per worker, k( + n ) ksf(k)k*
47The impact of population growth Investment, break-even investment( +n2) k( +n1) kAn increase in n causes an increase in break-even investment,sf(k)k2*leading to a lower steady-state level of k.k1*Capital per worker, k
48Prediction: Higher n lower k*. And since y = f(k) , lower k* lower y*.Thus, the Solow model predicts that countries with higher population growth rates will have lower levels of capital and income per worker in the long run.
49International evidence on population growth and income per person 100,000per Personin 2000(log scale)10,0001,000Figure 7-13, p Number of countries = 96. Source: Penn World Table version 6.1.10012345Population Growth
50The Golden Rule with population growth To find the Golden Rule capital stock, express c* in terms of k*:c* = y* i*= f (k* ) ( + n) k*c* is maximized when MPK = + nor equivalently, MPK = nIn the Golden Rule steady state, the marginal product of capital net of depreciation equals the population growth rate.
52Supply-side Effects of Fiscal Policy From a supply-side viewpoint, the marginal tax rate is of crucial importance:A reduction in marginal tax rates increases the reward derived from added work, investment, saving, and other activities that become less heavily taxed.High marginal tax rates will tend to retard total output because they will:discourage work effort and reduce the productive efficiency of labor,adversely affect the rate of capital formation and the efficiency of its use, and,encourage individuals to substitute less desired tax-deductible goods for more desired non-deductible goods.
53Supply-side Effects of Fiscal Policy So, changes in marginal tax rates, particularly high marginal rates, may exert an impact on aggregate supply because the changes will influence the relative attractiveness of productive activity in comparison to leisure and tax avoidance.Impact of supply-side effects:Usually take place over a lengthy time period.There is some evidence that countries with high taxes grow more slowly—France and Germany versus United Kingdom.While the significance of supply-side effects are controversial, there is evidence they are important for taxpayers facing extremely high tax rates – say rates of 40 percent or above.
54Goods & Services (real GDP) Supply Side Economics and Tax RatesLRAS1LRAS2Price LevelSRAS1AD2SRAS2With time, lower tax rates promote more rapid growth (shifting LRAS and SRAS out to LRAS2 and SRAS2).E1P0E2AD1Goods & Services (real GDP)YF1YF2What are the supply-side effects of a cut in marginal tax rates?Lower marginal tax rates increase the incentive to earn and use resources efficiently. AD1 shifts out to AD2, and SRAS & LRAS shift to the right.If the tax cuts are financed by budget deficits, AD may expand by more than supply, bringing an increase in the price level.
55Share of Taxes Paid By the Rich Share of personal income taxes paid by top ½ % of earners1997 Capital gains tax rate cut30 %Top rate raised from 30% to 39%28 %26 %1986 Top rate cut from 50% to 30%24 %Top rate cut from 91% to 70%22 %20 %18 %1981 Top rate cut from 70% to 50%16 %14 %196019651970197519801985199019952000The share of personal income taxes paid by the top one-half percent of earners is shown here.During the last four decades, the share of taxes paid by these earners has increased as the top tax rates have declined. This indicates that the supply side effects are strong for these taxpayers.
56Have Supply-siders Found a Way to Soak the Rich? Since 1986 the top marginal personal income tax rate in the United States has been less than 40% compared to 70% or more prior to that time.Nonetheless, the top one-half percent of earners have paid more than 25% of the personal income tax every year since 1997.This is well above the 14% to 19% collected from these taxpayers in the 1960s and 1970s when much higher marginal personal income tax rates were imposed on the rich.