宏经教材答案英文第八版.doc

多恩布什《宏观经济学》习题答案
刘秋红、杨燕风根据英文第8版修订。【注：红色字体的是后来修订的。】
第1章 导论
二、概念题
答：在解释产出和价格是如何决定时，通常可以用AS-AD模型解决，但是必须首先明确所考虑的时间是怎样的。
垂直的AS曲线描述的是长期的情况，产出Y只由总供给曲线AS决定——简单地说，长期的总产出Y（也叫总产量、总产值）固定于潜在产出或称充分就业产出Y*，即长期的Y不变（但这实际上是错误的！）；而价格是由需求和供给水平共同决定的。实际上在长期，总产出Y并不是没有变化——因为长期是由短期、中期构成的，所以长期中各时点的产出围绕Y*波动。因此垂直的AS曲线只是一种理想而简单的描述，实际上并不存在。【注：这些红色字体的是后来修订的。】水平的AS曲线描述的是短期的情形，此时产出由总需求决定，价格是固定不变的。向上倾斜的AS曲线描述的是中期情形，总供给和总需求的波动会影响生产能力和价格水平既定不变条件下的实际产量。
AD-AS模型是对现实世界的非常简单的陈述，它无法描述所有居民和经济中的企业行为。在这个框架中，总需求变动对产量和价格的影响在很大程度上取决于AS曲线的斜率。应该记住，当潜在产出能力提升时，特长期AS曲线会逐年向右移动，因此，即使在AD曲线固定不变时，价格水平会随着时间的推移而下降。

三、 技术题
答：产出缺口被定义为实际GDP和潜在GDP的差额。因此在该假设的经济中产出缺口为360亿美元（=1560-1200）。预计失业水平比正常水平高。

第2章 国民收入核算
二、概念题
1. Government transfer payments (TR) do not arise out of any production activity and are thus not counted in the value of GDP. If the government hired the people who currently receive transfer payments, then their wages would be counted as part of government purchases (G), which is counted in GDP. Therefore GDP would rise.

2.a. If the firm buys a car for an executive's use, the purchase counts as investment (I). But if the firm pays the executive a higher salary and she then buys a car, the purchase is counted as consumption (C).

2.b. The services that a homemaker provides are not counted in GDP (regardless of their value). However, if an individual officially hires his or her spouse to perform household duties at a certain wage rate, then the wages earned will be counted in GDP and GDP will increase.

2.c. If you buy a German car, consumption (C) will increase but net exports (NX = X - Q) will decrease. Overall GDP will increase by the value added at the foreign car dealership, since the import price is likely to be less than the sales price. If you buy an American car, consumption and thus GDP will increase. (Note: If the car you buy comes out of the car dealer's inventory, then the increase in C will be partially offset be a decline in I, and GDP will again only increase by the value added.)

3. GDP is the market value of all final goods and services currently produced within the country. (The U.S. GDP includes the value of the Hondas produced by a Japanese-owned assembly plant that is located in the U.S., but it does not include the value of Nike shoes that are produced by an American-owned shoe factory located in Malaysia.)
GNP is the market value of all final goods and services currently produced using assets owned by domestic residents. (Here the value of the Hondas produced by a Japanese-owned Honda plant is not counted but the value of the Nikes by the American-owned shoe plant is.)
Neither is necessarily a better measure of the output of a nation. The actual value of the GDP and GNP for the U.S. is fairly close.

4. The NDP (net domestic product) is defined as GDP minus depreciation. Depreciation measures the value of the capital that wears out during the production process and has to be replaced. Therefore NDP comes closer to measuring the net amount of goods produced in this country. If this is what you want to measure, then NDP should be used.

5. Increases in real GDP do not necessarily mean increases in welfare. For example, if the population of a country increases by more than real GDP, then the population of the country is on average worse off. Also some increases in output come from welfare reducing events. For example, increased pollution may cause more lung cancer, and the treatment of the lung cancer will contribute to GDP. Similarly, an increase in crime may lead to overtime work for police officers, whose increased salary will increase GDP. But the welfare of the people in the country may not have increased in either case. On the other hand, GDP does not always accurately measure quality improvements in goods or services (faster computers or improved health care) that improve people's welfare.

6. The CPI (consumer price index) and the PPI (producer price index) are both measured by looking at a certain market basket. The CPI's basket contains mostly finished goods and services that consumers tend to buy regularly in their daily lives. The PPI’s basket contains raw materials and semi-finished goods, that is, it measures costs to the producer of a product and its first user. The CPI is a concurrent economic indicator, whereas the PPI is a leading economic indicator.

7. The GDP-deflator is a price index that covers the average price increase of all final goods and services currently produced within an economy. It is defined as the ratio of current nominal GDP to current real GDP. Nominal GDP is measured in current dollars, while real GDP is measured in so-called base-year dollars. Even though early estimates of the GDP-deflator tend to be unreliable, the GDP-deflator can be a more useful price index than the CPI or PPI (both of which are fixed market baskets). This is true for two reasons: first it measures a much wider cross-section of goods and services; second, a fixed market basket cannot account for people substituting away from goods whose relative prices have changed, while the GDP-deflator, which includes all goods and services produced within the country, can.

8. If nominal GDP has suddenly doubled, it is most likely due to an increase in the average price level. Therefore, the first thing you would want to check is by how much the GDP-deflator has changed, to calculate by how much real output (GDP) has changed. If nominal GDP and the GDP-deflator have both doubled, then real GDP should be the same.

9. Assume the loan you made yields you an annual nominal return of 7%. If the rate of inflation is 4%, then your rate of return in real terms is only 3%. If, on the other hand, if inflation rate is 10%, then you will actually get a negative real rate of return, that is, you will lose 3% of your purchasing power. One way to protect yourself against such a loss of purchasing power is to adjust the interest rate for inflation, that is, to index the loan. In other words, you can require that, in addition to the specified interest rate of the loan of, let’s say, 3%, the borrower also has to pay an inflation premium equal to the percentage change in the CPI. In this case, a real rate of return of 3% would be guaranteed.

三、 技术题

1. The text calculates the change in real GDP in 1992 prices in the following way:

[RGDP01 - RGDP92]/RGDP92 = [3.50 - 1.50]/1.50 = 1.33 = 133%.

To calculate the change in real GDP in 2001 prices, we first have to calculate the GDP of 1992 in 2001 prices. Thus we take the quantities consumed in 1992 and multiply them by the prices of 2001, as follows:

Beer 1 at $2.00 = $2.00
Skittles 1 at $0.75 = $0.75
_______________________________
Total $2.75

The change in real GDP can now be calculated as

[6.25 - 2.75]/2.75 = 1.27 = 127%.

We can see that the growth rate of real GDP calculated this way is roughly the same as the growth rate calculated above.

2.a. The relationship between private domestic saving, investment, the budget deficit and net exports is shown by the following identity:

S - I º (G + TR - TA) + NX.

Therefore, if we assume that transfer payments (TR) remain constant, then an increase in taxes (TA) has to be offset either by an increase in government purchases (G), a decrease in net exports (NX), or a decrease in the difference between saving (S) and investment (I).

2.b. From the equation YD º C + S it follows that an increase in disposable income (YD) will be reflected in an increase in consumption (C), saving (S), or both.

2.c. From the equation YD º C + S it follows that when either consumption (C) or saving (S) increases, disposable income (YD) must increase as well.

3.a. Since depreciation D = Ig - In = 800 - 200 = 600 ==>

NDP = GDP - D = 6,000 - 600 = 5,400

3.b. From GDP = C + I + G + NX ==> NX = GDP - C - I - G ==>

NX = 6,000 - 4,000 - 800 - 1,100 = 100.

3.c. BS = TA - G - TR ==> (TA - TR) = BS + G ==> (TA - TR) = 30 + 1,100 = 1,130

3.d. YD = Y - (TA - TR) = 5,400 - 1,130 = 4,270

3.e. S = YD - C = 4,270 - 4,000 = 270

4.a. S = YD - C = 5,100 - 3,800 = 1,300

4.b. From S - I = (G + TR - TA) + NX ==> I = S - (G + TR - TA) - NX = 1,300 - 200 - (-100) = 1,200.

4.c. From Y = C + I + G + NX ==> G = Y - C - I - NX ==>

G = 6,000 - 3,800 - 1,200 - (-100) = 1,100.

Also: YD = Y - TA + TR ==> TA - TR = Y - YD = 6,000 - 5,100 ==> TA - TR = 900

From BS = TA - TR - G ==> G = (TA - TR) - BS = 900 - (-200) ==> G = 1,100

5. According to Equation (2) in the text, the value of total output (in billions of dollars) can be calculated as: Y = labor payments + capital payments + profits = $60 + $20 + $0 = $80

6.a. Since nominal GDP is defined as the market value of all final goods and services currently produced in this country, we can only measure the value of the final product (bread), and therefore we get $2 million (since 1 million loaves are sold at $2 each).

6.b. An alternative way of measuring total GDP would be to calculate all the value added at each step of production. The total value of the ingredients used by the bakeries can be calculated as:

1,200,000 pounds of flour ($1 per pound) = 1,200,000
100,000 pounds of yeast ($1 per pound) = 100,000
100,000 pounds of sugar ($1 per pound) = 100,000
100,000 pounds of salt ($1 per pound) = 100,000
__________________________________________________________
= 1,500,000

Since $2,000,000 worth of bread is sold, the total value added at the bakeries is $500,000.

7. If the CPI increases from 2.1 to 2.3, the rate of inflation can be calculated in the following way:

rate of inflation = (2.3 - 2.1)/2.1 = 0.095 = 9.5%

The CPI often overstates inflation, since it is calculated by using a fixed market basket of goods and services. But the fixed weights in the CPI's market basket cannot capture the tendency of consumers to substitute away from goods whose relative prices have increased. Therefore, the CPI will overstate the increase in consumers' expenditures.

8. The real interest rate (r) is defined as the nominal interest rate (i) minus the rate of inflation (p). Therefore the nominal interest rate is the real interest rate plus the rate of inflation, or

i = r + p = 3% + 4% = 7%.

第3章 增长与积累
二、概念题
1. The production function provides a quantitative link between inputs and output. For example, the Cobb-Douglas production function mentioned in the text is of the form:

Y = F(N,K) = AN1-qKq,

where Y represents the level of output. (1 - q) and q are weights equal to the shares of labor (N) and capital (K) in production, while A is often used as a measure for the level of technology. It can be easily shown that labor and capital each contribute to economic growth by an amount that is equal to their individual growth rates multiplied by their respective share in income.

2. The Solow model predicts convergence, that is, countries with the same production function, savings rate, and population growth will eventually reach the same level of income per capita. In other words, a poor country may eventually catch up to a richer one by saving at the same rate and making technological innovations. However, if these countries have different savings rates, they will reach different levels of income per capita, even though their long-term growth rates will be the same.

3. A production function that omits the stock of natural resources cannot adequately predict the impact of a significant change in the existing stock of natural resources on the economic performance of a country. For example, the discovery of new oil reserves or an entirely new resource would have a significant effect on the level of output that could not be predicted by such a production function.

4. Interpreting the Solow residual purely as technological progress would ignore, for example, the impact that human capital has on the level of output. In other words, this residual not only captures the effect of technological progress but also the effect of changes in human capital (H) on the growth rate of output. To eliminate this problem we can explicitly include human capital in the production function, such that

Y = F(K,N,H) = ANaKbHc with a + b + c = 1.

Then the growth rate of output can be calculated as

DY/Y = DA/A + a(DN/N) + b(DK/K) + c(DH/H).

5. The savings function sy = sf(k) assumes that a constant fraction of output is saved. The investment requirement, that is, the (n + d)k-line, represents the amount of investment needed to maintain a constant capital-labor ratio (k). A steady-state equilibrium is reached when saving is equal to the investment requirement, that is, when sy = (n + d)k. At this point the capital-labor ratio k = K/N is not changing, so capital (K), labor (N), and output (Y) all must be growing at the same rate, that is, the rate of population growth n = (DN/N).

6. In the long run, the rate of population growth n = (DN/N) determines the growth rate of the steady-state output per capita. In the short run, however, the savings rate, technological progress, and the rate of depreciation can all affect the growth rate.

7. Labor productivity is defined as Y/N, that is, the ratio of output (Y) to labor input (N). A surge in labor productivity therefore occurs if output grows at a faster rate than labor input. In the U.S. we have experienced such a surge in labor productivity since the mid-1990s due to the enormous growth in GDP. This surge can be explained from the introduction of new technologies and more efficient use of existing technologies. Many claim that the increased investment in and use of computer technology has stimulated economic growth. Furthermore, increased global competition has forced many firms to cut costs by reorganizing production and eliminating some jobs. Thus, with large increases in output and a slower rate of job creation we should expect labor productivity to increase. (One should also note that a higher-skilled labor force also can contribute to an increase in labor productivity, since the same number of workers can produce more output if workers are more highly skilled.)

三、技术题
1.a. According to Equation (2), the growth of output is equal to the growth in labor times the labor share plus the growth of capital times the capital share plus the rate of technical progress, that is,

DY/Y = (1 - q)(DN/N) + q(DK/K) + DA/A, where

1 - q is the share of labor (N) and q is the share of capital (K). Thus if we assume that the rate of technologic