多恩布什 宏观经济学 第十版 英文课件Chapter_14

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Real cost of capital = nominal interest rate - nominal capital gain
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At the time the firm makes an investment, the nominal interest rate is known, but the inflation rate for the coming year is not e • Real cost of borrowing is the expected real interest rate: r = i − π Capital wears out over time → must include depreciation, d The complete formula for the rental cost of capital is:
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Capital Stock Adjustment
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To increase the capital stock from K-1 to K0, the firm must achieve net investment of
I ≡ ( K0 − K −1 ) = ( K −1 + λ ( K * − K −1 )) − K −1 = λ ( K * − K −1 )
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Both GDP and investment are flow variables
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Capital is the dollar value of all the buildings, machines, and inventories at a given point in time → stock value
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Chapter 14
Investment Spending
• • • • Item Item Item Etc.
McGraw-Hill/Irwin Macroeconomics, 10e
14-2 © 2008 The McGraw-Hill Companies, Inc., All Rights Reserved.
14-4
The Desired Capital Stock
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Firms use capital, along with labor and other resources, to produce output → The goal of a given firm is to maximize profits
14-9
Capital Stock Adjustment
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To increase the capital stock from K-1 to K0, the firm must achieve net investment of
I ≡ ( K0 − K −1 ) = ( K −1 + λ ( K * − K −1 )) − K −1 = λ ( K * − K −1 )
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Investment Subsectors
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Figure 14-6 demonstrates the volatility of the three investment subsectors:
1. 2. 3.
[Insert Figure 14-6 here]
Business fixed investment Residential investment Inventory investment Business fixed investment is the largest of the three Inventory investment is the most volatile
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In this chapter we study how investment depends on interest rates and income Figure 14-1 illustrates the volatility of investment by comparing investment and GDP
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Investment is the amount spent by businesses to add to the existing capital stock over a given period
Flow of investment is quite small compared to the stock of capital.
Introduction
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Investment:

[Insert Figure 14-1 here]
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Links the present to the future Links the goods and money markets Drives much of the business cycle
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rc = r + d = iof capitaldis −π e + The complete formula for the rental cost
The Desired Stock of Capital
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Firms add capital until the marginal return of the last unit added drops to the rental cost of capital
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Capital Stock Adjustment
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The flexible accelerator model can be used to explain the speed at which firms plan to adjust their capital stock
Basic
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Introduction
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The theory of investment is the theory of the demand for capital
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Investment is the flow of spending that adds to the stock of capital
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The Desired Capital Stock
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To derive the rental cost of capital:
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firms finance the purchase of capital by borrowing over time, at an interest rate of i In the presence of inflation, the nominal dollar value of capital rises over time
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[Insert Figure 14-4 here]
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At the initial level of capital, K0, the price of capital is just high enough to generate enough investment, I0, to replace the depreciating capital In the LR, supply of new capital is very elastic, so the increase in demand is met without much change in price In the SR, price rises to P1, increasing investment flow to I1
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Capital at the end of last period is K-1 The gap between actual and desired capital stock is (K*-K-1) A firm plans to add a fraction of the gap to last periods stock Actual capital stock at the end of the current period is then K 0 = K −1 + λ ( K * − K −1 ) (2)
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The general relationship among the desired capital stock, K*, rc, and output is K * = g ( rc, Y ) (1)
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From Desired Capital Stock to Investment
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Figure 14-4 illustrates an increase in the demand for capital stock as a rightward shift in the demand for capital schedule
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[Insert Figure 14-2 here]
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Diminishing marginal product of capital means that each successive unit of capital yields less than the previous unit → Figure 14-2 An increase in the rental cost of capital can only be justified by an increase in the marginal product of capital, and a lower level of K
The marginal product of capital is the increase in output produced by using 1 more unit of capital in production. The rental (user) cost of capital is the cost of using 1 more unit of capital in production.