CH4,5货币和通货膨胀

V V
M V P Y
CHAPTER 4 Money and Inflation
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货币数量论
M V P Y
价格水平是如何决定的:
由于 V 是常数, 货币供给决定了名义GDP (P
Y )。
实际 GDP (Y) 由经济中K 和 L 的供给以及生产
函数来决定 (第3章)。
CHAPTER 4 Money and Inflation
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4.4 Inflation and interest rates
Nominal interest rate, i
not adjusted for inflation
Real interest rate, r
adjusted for inflation:
那么，为什么通膨是一个 社会问题呢？
CHAPTER 4 Money and Inflation
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通膨的社会成本
通膨的社会成本可以分为两类：
1. 预期到的通胀的成本 2. 未预期到的通胀的成本
CHAPTER 4 Money and Inflation
causes an equal increase in i.
This one-for-one relationship
is called the Fisher effect.
CHAPTER 4 Money and Inflation
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Two real interest rates
Hence, the nominal interest rate relevant for money demand is r + E
CHAPTER 4 Money and Inflation
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Equilibrium
(M/P) = L( r + E , Y)
The supply of real money balances
货币流通速度概念：货币周转(流通)的速度(转手的次
数)
定义：在给定的时间内每一块钱的平均易手次数
例如：2007年 交易总量为$500 billion （P x T） 货币供给= $100 billion (M) 2007年平均每元钱参与了五次交易 因此，货币流通速度 = 5
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The money demand function
(M P )d L(i ,Y ) = L( r + E , Y)
When people are deciding whether to hold money or bonds, they don’t know what inflation will turn out to be.
4.1 什么是货币 货币 不等于 财富 职能：价值储藏手段, 计价单位, 交换媒介 货币类型：法定货币（fiat money),
商品货币（commodity money） ex. gold
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4.1 什么是货币 控制货币（供给）数量：公开市场操作(买卖政府
债券)
宽松货币政策 vs. 紧缩货币政策 货币（money）包括：通货（currency）,M1, M2
Real money demand
CHAPTER 4 Money and Inflation
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What determines what
(M/P) = L( r + E , Y)
variable M r Y P
how determined (in the long run)
exogenous (the Fed)


M M

Y Y
正常的经济增长要求一定的货币增长来支持交易
的增长。
货币增长若是超过这个量就会导致通货膨胀。
CHAPTER 4 Money and Inflation
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货币数量论


M M

Y Y
Y/Y 依赖于生产要素的增长和技术进步，而它们 被假定为常量（长期）。
i – = ex post real interest rate:
the real interest rate actually realized
So, in Ch3, S=I decides r and i=r + E
CHAPTER 4 Money and Inflation
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The “revenue” raised from printing money
is called seigniorage (pronounced SEEN-your-idge).
The inflation tax:
Printing money to raise revenue causes inflation. Inflation is like a tax on people who hold money.
= actual inflation rate
(not known until after it has occurred)
E= expected inflation rate
i – E= ex ante real interest rate:
the real interest rate people expect at the time they buy a bond or take out a loan
CHAPTER 4 Money and Inflation
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4.2 货币的数量论(quantity theory of money)
数量方程
M V = P T 源自于前面关于货币流通速度的定义。
其中
V = 货币流通速度; M = 货币供给 P = 价格; T = 交易次数; PT = 交易总值
通胀使实际工资降低了
这只有在短期，当名义工资（W）被合同固定时
才成立。
(Chap. 3) 在长期，实际工资是由劳动供给和劳
动的边际产量而不是由价格水平或通胀来决定的。
CHAPTER 4 Money and I古典的观点:
价格水平的变动仅仅是衡量单位的变动而已。
the nominal interest rate, i.
the opportunity cost of holding money (instead
of bonds or other interest-earning assets).
Hence, i in money demand.
货币需求:
(M/P )d = k Y
数量方程:
M V = P Y
二者之间的联系: k = 1/V
当人们持有较多的货币(k 较高)时，货币转手的次
数就较少 (V 较小).
CHAPTER 4 Money and Inflation
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货币的数量论
从数量方程式开始 假定 V 是常数且外生决定: 根据这个假定, 数量方程式可以写为
因此，货币数量论认为从长期来看，通货 膨胀完全是由货币供给增加引起的。
CHAPTER 4 Money and Inflation
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4.3 货币铸造税（seigniorage）
To spend more without raising taxes or selling
bonds, the govt can print money.
r = i
CHAPTER 4 Money and Inflation
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The Fisher effect
The Fisher equation: i = r + Chap 3: S = I determines r. Hence, an increase in
4.5 Money demand and the nominal interest rate
In the quantity theory of money,
the demand for real money balances depends only on real income Y.
Another determinant of money demand:
CHAPTER 4 Money and Inflation
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The money demand function
(M P )d L(i ,Y )
(M/P )d = real money demand, depends
negatively on i
i is the opp. cost of holding money
positively on Y
higher Y more spending so, need more money
(“L” is used for the money demand function because money is the most liquid asset.)
CHAPTER 4 Money and Inflation
所以价格水平
P = (名义 GDP)/(实际 GDP).
CHAPTER 4 Money and Inflation
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货币数量论
由于：
乘积的增长率等于增长率的乘积。
所以，数量方程的增长率可以写为:
M V P Y
MV
PY
货币数量论假定V 是常数, 因此 V = 0