1. 11 THE MACROECONOMICS OF OPEN ECONOMIES Chapter 31 Open-Economy Macroeconomics: Basic Concepts

2. Open-Economy Macroeconomics: Basic Concepts
Open and Closed Economies
A closed economy is one that does not interact with other economies in the world.
There are no exports, no imports, and no capital flows.
An open economy is one that interacts freely with other economies around the world

3. Open-Economy Macroeconomics: Basic Concepts
An Open Economy
An open economy interacts with other countries in two ways.
It buys and sells goods and services in world product markets.
It buys and sells capital assets in world financial markets

4. 31.1 The International Flow of Goods and Capital
An Open Economy
The United States is a very large and open economy—it imports and exports huge quantities of goods and services.
Over the past four decades, international trade and finance have become increasingly important.

5. 31.1.1 The Flow of Goods: Exports, Imports, Net Exports
Exports are goods and services that are produced domestically and sold abroad.
Imports are goods and services that are produced abroad and sold domestically.

6. 31.1.1 The Flow of Goods: Exports, Imports, Net Exports
Net exports (NX) are the value of a nation’s exports minus the value of its imports.
Net exports are also called the trade balance贸易余额.

7. 31.1.1 The Flow of Goods: Exports, Imports, Net Exports
A trade deficit贸易赤字 is a situation in which net exports (NX) are negative.
Imports > Exports
A trade surplus贸易盈余 is a situation in which net exports (NX) are positive.
Exports > Imports
Balanced trade平衡贸易　refers to when net exports are zero—exports and imports are exactly equal.

8. 31.1.1 The Flow of Goods: Exports, Imports, Net Exports
Factors That Affect Net Exports
The tastes of consumers for domestic and foreign goods.
The prices of goods at home and abroad.
The exchange rates at which people can use domestic currency to buy foreign currencies.
The incomes of consumers at home and abroad.
The costs of transporting goods from country to country.
The policies of the government toward international trade.

9. Figure 1 The Internationalization of the U.S. Economy
Percent
of GDP 15
Imports 10
Exports 5
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000

10. Figure2. The Internationalization of the China Economy

11. 31.1.2 The Flow of Financial Resources: Net Capital Outflow
Net capital outflow资本净流出 refers to the purchase of foreign assets by domestic residents minus the purchase of domestic assets by foreigners.
A U.S. resident buys stock in the Toyota corporation and a Mexican buys stock in the Ford Motor corporation.

12. 31.1.2 The Flow of Financial Resources: Net Capital Outflow
When a U.S. resident buys stock in Telmex, the Mexican phone company, the purchase raises U.S. net capital outflow.
When a Japanese residents buys a bond issued by the U.S. government, the purchase reduces the U.S. net capital outflow.

13. 31.1.2 The Flow of Financial Resources: Net Capital Outflow
Variables that Influence Net Capital Outflow.
The real interest rates being paid on foreign assets.
The real interest rates being paid on domestic assets.
The perceived economic and political risks of holding assets abroad.
The government policies that affect foreign ownership of domestic assets.

14. 31.1.3 The Equality of Net Exports and Net Capital Outflow
Net exports (NX) and net capital outflow (NCO) are closely linked.
For an economy as a whole, NX and NCO must balance each other so that:
NCO = NX
This holds true because every transaction that affects one side must also affect the other side by the same amount.

15. 31.1.3 The Equality of Net Exports and Net Capital Outflow
To see why this accounting identity is true, consider an example.Suppose that Boeing, the U.S.aircraft maker, sells some planes to a Japanese airline. In this sale, a U.S.company gives planes to a Japanese company, and a Japanese company gives yen to a U.S. Company. Notice that two things have occurred simultaneously. The U.S. has sold to a foreigner some of its output(the planes), and this sale increases U.S. Net exports. In addition, the U.S. has acquired some foreign assets(the yen), and this acquisition increases U.S. Net capital outflow.

16. 31.1.3 The Equality of Net Exports and Net Capital Outflow
The equality of net exports and net capital outflow follows from the fact that every international transaction is an exchange. When a seller country transfers a good or service to a buyer country, the buyer country gives up some asset to pay for this good or service. The value of that asset equals the value of the good or service sold. When we add everything up, the net value of goods and services sold by a country (NX) must equal the net value of assets acquired(NCO). The international flow of goods and services and the international flow of capital are two sides of the same coin.

17. 31.1.4 Saving, Investment, and Their Relationship to the International Flows
Net exports is a component of GDP:
Y = C + I + G + NX
National saving is the income of the nation that is left after paying for current consumption and government purchases:
Y - C - G = I + NX

18. Saving = Domestic Investment + Net Capital Outflow
Saving, Investment, and Their Relationship to the International Flows
National saving (S) equals Y - C - G so:
S = I + NX or
S = I NCO
Saving = Domestic Investment + Net Capital Outflow
This equation shows that a nation’s saving must equal its domestic investment plus its net capital outflow. In other words, when Chinese citizens save a dollar of their income for the future, that dollar can be used of finance accumulation of domestic capital or it can be used to finance the purchase of capital abroad.

19. Figure 2 National Saving, Domestic Investment, and Net Foreign Investment
(a) National Saving and Domestic Investment (as a percentage of GDP)
Percent
of GDP 20
Domestic investment 18 16 14
National saving 12 10
1960
1965
1970
1975
1980
1985
1990
1995
2000

20. Figure 2 National Saving, Domestic Investment, and Net Foreign Investment
(b) Net Capital Outflow (as a percentage of GDP)
Percent
of GDP 4 3 2
Net capital
outflow 1 –1 –2 –3 –4
1960
1965
1970
1975
1980
1985
1990
1995
2000

21. Summing Up
Consider first a country with a trade surplus. By definition, a trade surplus means that the value of exports exceeds the value of imports. Because net exports are exports minus imports, net exports(NX) are greater than zero. As a result, income(Y=C+I+G +NX) must be greater than domestic spending (C+I+G). But if Y is more than C+I+G, then(Y-C-G) must be more than I. That is, saving (S=Y-C-G) must exceed investment. Because the country is saving more than it is investing, it must be sending some of its saving abroad. That is, the net capital outflow must be greater than zero.

22. Summing Up
The converse logic applies to a country with a trade deficit. By definition, a trade deficit means that the value of exports are less than the value of imports. Because net exports are exports minus imports, net exports(NX) are negative.Thus, income(Y=C+I+G +NX) must be less than domestic spending (C+I+G). But if Y is less than C+I+G, then(Y-C-G) must be less than I. That is, saving (S=Y-C-G) must less than investment. Because the country is saving less than it is investing, it must be attracting some of its saving abroad. That is, the net capital outflow must be negative.

23. Summing Up

24. 31.2 The Prices for International Transactions: Real and Nominal Exchange Rates
International transactions are influenced by international prices.
The two most important international prices are the nominal exchange rate and the real exchange rate.

25. 31.2.1 Nominal Exchange Rates
The nominal exchange rate is the rate at which a person can trade the currency of one country for the currency of another.
The nominal exchange rate is expressed in two ways:
In units of foreign currency per one U.S. dollar.
And in units of U.S. dollars per one unit of the foreign currency.

26. 31.2.1 Nominal Exchange Rates
Assume the exchange rate between the Japanese yen and U.S. dollar is 80 yen to one dollar.
One U.S. dollar trades for 80 yen.
One yen trades for 1/80 (= ) of a dollar.

27. 31.2.1 Nominal Exchange Rates
If the exchange rate changes so that a dollar buys more foreign currency, that change is called an appreciation of the dollar.
Appreciation refers to an increase in the value of a currency as measured by the amount of foreign currency it can buy.
If the exchange rate changes so that a dollar buys less foreign currency, that change is called an depreciation of the dollar.
Depreciation refers to a decrease in the value of a currency as measured by the amount of foreign currency it can buy.

28. 31.2.1 Nominal Exchange Rates
If a dollar buys more foreign currency, there is an appreciation of the dollar.
If it buys less there is a depreciation of the dollar.

29. Real Exchange Rates
The real exchange rate is the rate at which a person can trade the goods and services of one country for the goods and services of another.
If a case of German beer is twice as expensive as American beer, the real exchange rate is 1/2 case of German beer per case of American beer.

30. Real Exchange Rates
The real exchange rate compares the prices of domestic goods and foreign goods in the domestic economy.
The real exchange rate depends on the nominal exchange rate and the prices of goods in the two countries measured in local currencies.

31. Real Exchange Rates
Suppose that a bushel of American rice sells for $100, and a bushel of Japanese rice sell $16,000 yen. What is the real exchange rate between American and Japanese rice?
Bushel: measure for grain and fruit (8 gallons or about 36.4 litres)

32. Real Exchange Rates
The real exchange rate is a key determinant of how much a country exports and imports.
Foreign Price
Real exchange rate=
Nominal exchange rate Domestic price
16,000 yen per bushel of Japanese rice
Real exchange rate=
(80 yen per dollar)
($100per bushel of American rice) =
8000 yen per bushel of American rice
= 1/2 bushel of Japanese rice
per bushel of American rice.

33. Real Exchange Rates
A depreciation (fall) in the U.S. real exchange rate means that U.S. goods have become cheaper relative to foreign goods.
This encourages consumers both at home and abroad to buy more U.S. goods and fewer goods from other countries.

34. Real Exchange Rates
As a result, U.S. exports rise, and U.S. imports fall, and both of these changes raise U.S. net exports.
Conversely, an appreciation in the U.S. real exchange rate means that U.S. goods have become more expensive compared to foreign goods, so U.S. net exports fall.

38. 1985年
统一为10%
1987年
从10%上调为12%
1988年
从12%上调为13%
1998年3月21日
 从12%下调为8%
1999年11月21日
从8%下调为6%
2003年9月21日
从6%上调为7%
2004年4月25日
从7%上调为7.5%
2006年7月5日
 从7.5%上调为8%
2006年8月15日
从8%上调为8.5%
2006年11月15日
 从8.5%上调为9%
2007年1月15日
 从9%上调为9.5%
2007年2月25日
从9.5％上调为10％
2007年4月16日
从10％上调为10.5％
2007年5月15日
从10.5％上调为11％
2007年6月5
从11％上调为11.5％

39. 31.3 A FIRST THEORY OF EXCHANGE-RATE DETERMINATION: PURCHASING-POWER PARITY
The purchasing-power parity theory is the simplest and most widely accepted theory explaining the variation of currency exchange rates.
Purchasing-power parity is a theory of exchange rates whereby a unit of any given currency should be able to buy the same quantity of goods in all countries.

40. 31.3.1 The Basic Logic of Purchasing-Power Parity
The theory of purchasing-power parity is based on a principle called the law of one price. This law asserts that a good must sell for the same price in all locations.

41. 31.3.1 The Basic Logic of Purchasing-Power Parity
If the law of one price were not true, unexploited profit opportunities would exist.
The process of taking advantage of differences in prices in different markets is called arbitrage 套利.

42. 31.3.1 The Basic Logic of Purchasing-Power Parity
If arbitrage occurs, eventually prices that differed in two markets would necessarily converge.
According to the theory of purchasing-power parity, a currency must have the same purchasing power in all countries and exchange rates move to ensure that.

43. 31.3.2 Implications of Purchasing-Power Parity
Suppose that P is the price of a basket of goods in the US. (measured in dollars), P* is the price of a basket of goods in Japan (measured in yen), and e is the nominal exchange rate (the number of yen a dollar can buy). Now consider the quantity of goods a dollar can buy at home and abroad. At home, the price level is P, so the purchasing power of $1 at home is 1/P. Abroad, a dollar can be exchanged into e units of foreign currency, which in turn have purchasing power e/P*. For the purchasing power of a dollar to be the same in the two countries, it must be the case that
1/ P = e / P*

44. 31.3.2 Implications of Purchasing-Power Parity
1/ P = e /P*
With rearrangement, this equation becomes
1 = eP / P*
Notice that the left-hand side of this equation is a constant, and the right-hand side is the real exchange rate. Thus, If the purchasing power of the dollar is always the same at home and abroad, then the exchange rate----the relative price of domestic and foreign goods---- cannot change.

45. 31.3.2 Implications of Purchasing-Power Parity
1 = eP / P*
We can rearrange the equation to solve for the nominal exchange rate:
e = P* / P
That is, the nominal exchange rate equals the ratio of the foreign price level (measured in units of the foreign currency) to the domestic price level (measured in units of the domestic currency). According to the theory of purchasing-power parity, the nominal exchange rate between the currencies of two countries must reflect the different price levels in those countries.

46. 31.3.2 Implications of Purchasing-Power Parity
A key implication of this theory is that nominal exchange rates change when price levels change. The price level in any country adjusts to bring the quantity of money supplied and the quantity of money demanded into balance.
When the central bank prints large quantities of money, the money loses value both in terms of the goods and services it can buy and in terms of the amount of other currencies it can buy.

47. Figure 3 Money, Prices, and the Nominal Exchange Rate During the German Hyperinflation
Indexes
(Jan. 1921 5
100)
1,000,000,000,000,000
Money supply
10,000,000,000
Price level
100,000 1
Exchange rate
.00001
1921
1922
1923
1924
1925

48. 31.3.3 Limitations of Purchasing-Power Parity
Purchasing power provides a simple model of how exchange rates are determined.
Yet the theory of purchasing-power parity is not completely accurate. That is, exchange rates do not always move to ensure that a dollar has the same real value in all countries all the time.There are two reasons why the theory of purchasing-power parity does not always hold in practice.

49. 31.3.3 Limitations of Purchasing-Power Parity
The first reason is that many goods are not easily traded or shipped from one country to another.
The second reason that purchasing-power parity does not always hold is that even tradable goods are not always perfect substitutes when they are produced in different countries.
Eg. some consumers prefer German cars, and others prefer American cars. Moreover, consumer tastes can change over time.

50. Summary
Net exports are the value of domestic goods and services sold abroad minus the value of foreign goods and services sold domestically.
Net capital outflow is the acquisition of foreign assets by domestic residents minus the acquisition of domestic assets by foreigners

51. Summary
An economy’s net capital outflow always equals its net exports.
An economy’s saving can be used to either finance investment at home or to buy assets abroad.

52. Summary
The nominal exchange rate is the relative price of the currency of two countries.
The real exchange rate is the relative price of the goods and services of two countries.

53. Summary
When the nominal exchange rate changes so that each dollar buys more foreign currency, the dollar is said to appreciate or strengthen.
When the nominal exchange rate changes so that each dollar buys less foreign currency, the dollar is said to depreciate or weaken.

54. Summary
According to the theory of purchasing-power parity, a unit of currency should buy the same quantity of goods in all countries.
The nominal exchange rate between the currencies of two countries should reflect the countries’ price levels in those countries.

55. Mankiw - ch31 Questions for Review

56. 1. Define net exports and net capital outflow
1.Define net exports and net capital outflow. Explain how and why they are related. (Mankiw,3rd edition, p676,678,680)
2. Explain the relationship among saving, investment, and net capital outflow.(Mankiw,3rd edition, p )
3.What are nominal exchange rate and real exchange rates?
3. 如果日本汽车价格为50万日元，一辆类似的美国汽车价格为l万美元，而且，如果1美元可以兑换lO0日元，名义汇率与实际汇率是多少？
4. Describe the economic logic behind the theory of purchasing-powering parity.(Mankiw,3rd edition, p689)
5. 如果美联储开始大量印发美元，1美元所能购买的日元数量会有什么变化？