均衡价格理论的应用.docx

3.3 均衡价格理论的应用
微观经济学的核心是要论证通过价格机制能够对社会经济自发地做出合理的调节，事实上价格机制的调节作用并不像理论上所讲的那样完善，比如某些生活必须品严重短缺时，价格会大幅度提高，在此价格水平上，收入水平低的家庭便难以维持最低水平的生活，从而不利于社会稳定。因而政府有必要通过制定价格政策来克服这些副作用。政府常用的价格政策主要有限制价格和支持价格政策。
一、限制价格

Maximum price A price ceiling set by the government or some other agency. The price is not allowed to rise above this level (although it is allowed to fall below it).

Rationing Where the government restricts the amount of a good that people are allowed to buy.

The government may set maximum prices to prevent them from rising above a certain level. This will normally be done for reasons of fairness. In wartime, or times of famine, the government may set maximum prices for basic goods so that poor people can afford to buy them.

The resulting shortages, however, create further problems. If the government merely sets prices and does not intervene further, the shortages will lead to the following:
l Allocation on a ‘first come, first serve’ basis.
l Firms deciding which customers should be allowed to buy: for example, giving preference to regular customers.

Neither of the above may be considered fair. Certain needy people may be forced to go without. Therefore, the government may adopt a system of rationing. People could be issued with a set number of coupons for each item rationed.

A major problem with maximum prices is likely to be the emergence of black markets, where customers, unable to buy enough in legal markets, may well be prepared to pay very high prices.

Another problem is that the maximum prices reduce the quantity produced of an already scarce commodity.

To minimize these types of problem the government may attempt to reduce the shortage by encouraging supply: by drawing on stores, by direct government production, or by giving subsidies or tax relief to firms. Alternatively, it may attempt to reduce demand: by the production of more alternative goods or by controlling people’s incomes.

Minimum price A price floor set by the government or some other agency. The price is not allowed to fall below this level (although it is allowed to rise above it).

Black markets Where people ignore the government’s price and/or quantity controls and sell illegally at whatever price equates illegal demand and supply.

The government sets minimum prices to prevent them from falling below a certain level. It may do this for various reasons:
l To protect producers’ incomes.
l To create a surplus, e.g. grains. Particular in periods of glut, which can be stored in preparation for possible future shortages.
l In the case of wages (the price of labor), minimum wage legislations can be used to prevent workers’ wage rates from falling below a certain level.

The government can use various methods to deal with the surpluses associated with minimum prices.
l The government could buy the surplus and store it, destroy it or sell it abroad in another markets.
l Supply could be artificially lowered by restricting producers to particular quotas.
l Demand could be raised by advertising, by finding alternative uses for the goods, or by reducing consumption of substitute goods (e.g. by imposing taxes or quotas on substitutes, such as imports).

One of the problems with minimum prices is that firms with surpluses on their hands may try to evade the price control and cut their prices.

Another problem is that high prices may cushion inefficiency. Firms may feel less need to find more efficient methods of production and to cut their costs if their profits are being protected by the high price. Also the high price may discourage firms from producing alternative goods which they could produce more efficiently or which are in higher demand, but which nevertheless have a lower price.

限制价格是指政府为了限制某些生活必需品的物价上涨而规定的这些商品的最高价格，限制价格低于市场均衡价格。如图3-5所示，某商品由供求关系所决定的均衡价格为Po，均衡数量为Qo，但在这一价格水平时，部分生活贫困的人将买不起，因而政府对这一部分商品实行限制价格政策，限制价格为P1，P1＜Po，此时商品实际供给量为QS，需求量为QD，供给量小于需求量，产品供不应求。因而为了维持限制价格，政府就要实行配给制。
Eo
0 　 QD Qo QS Q
P

Po
P1

图3-5 限制价格及结果
Do
So
供给不足

限制价格的影响作用可以利用住房的限制价格为例来说明：
第一，导致住房供给严重不足。在计划经济体制下，决定住房供给的并不是价格，而是国家计划。所以，住房不足的基本原因不能完全归咎于租金的高低，但应该指出，除了计划失误外，房租过低也是原因之一。由于房租过低甚至比住房的维修费用还少，这就造成住房部门资金严重不足，建房困难。
第二，寻求活动、黑市和寻租。在房租受到严格管制，住房严重短缺的情况下，就会产生寻求活动和黑市。在我国公有单位住房是由各单位拥有的住房占绝大多数。在这种情况下，寻求活动就是：想尽办法分到国家住房，这种想办法走门子就是一种寻求活动。这种寻求活动增加了住房的交易成本。黑市活动包括两方面：以极高的价格租用私人住房，以及个人把分配到的住房高价出租。除了寻求活动和黑市外，在租金受到严格限制，住房采取配给的情况下，必然产生寻租现象。这就表现在，掌握分配住房的人，利用权力接受贿赂。
解决住房问题的出路，一是住房市场化。一方面通过有偿转让使公有住房私有化。另一方面开放对房租限制，由住房市场的供求决定房租。二是创造住房市场化条件。我国实行住房市场化，由于职工收入水平低，工资中实际不包括买房支出，以及住房的分配不公平等因素，造成严重困难。因而我们必须创造条件，推动住房市场化。
根据上述实例，对于限制价格的利弊可以概括如下：限制价格有利于社会平等的实现，有利于社会的安定。但这种政策长期实行会引起严重的不利后果。第一，价格水平低不利于刺激生产，从而会使产品长期存在短缺现象。第二，价格水平低不利于抑制需求，从而会在资源短缺的同时又造成严重的浪费。第三，限制价格之下所实行的配给，会引起社会风尚败坏，产生寻求活动、黑市和寻租。正因为以上原因，一般经济学家都反对长期采用限制价格政策，一般只在战争或自然灾害等特殊时期使用。
二、支持价格

Minimum price A price floor set by the government or some other agency. The price is not allowed to fall below this level (although it is allowed to rise above it).

Black markets Where people ignore the government’s price and/or quantity controls and sell illegally at whatever price equates illegal demand and supply.

The government sets minimum prices to prevent them from falling below a certain level. It may do this for various reasons:
l To protect producers’ incomes.
l To create a surplus, e.g. grains. Particular in periods of glut, which can be stored in preparation for possible future shortages.
l In the case of wages (the price of labor), minimum wage legislations can be used to prevent workers’ wage rates from falling below a certain level.

The government can use various methods to deal with the surpluses associated with minimum prices.
l The government could buy the surplus and store it, destroy it or sell it abroad in another markets.
l Supply could be artificially lowered by restricting producers to particular quotas.
l Demand could be raised by advertising, by finding alternative uses for the goods, or by reducing consumption of substitute goods (e.g. by imposing taxes or quotas on substitutes, such as imports).

One of the problems with minimum prices is that firms with surpluses on their hands may try to evade the price control and cut their prices.

Another problem is that high prices may cushion inefficiency. Firms may feel less need to find more efficient methods of production and to cut their costs if their profits are being protected by the high price. Also the high price may discourage firms from producing alternative goods which they could produce more efficiently or which are in higher demand, but which nevertheless have a lower price.

支持价格又称最低限价，是政府为了扶植某一行业的发展而规定的该行业产品的最低价格。支持价格高于市场均衡价格。如图3-6所示，该行业某商品由供求关系所决定的均衡价格为Po，均衡数量为Qo，政府为了扶植该行业的发展而制定的支持价格为P1，P1>Po，此时供给量为QS，需求量为QD，供给量大于需求量，产品出现过剩。为了防止价格下跌，政府就要收购剩余产品，因而支持价格政策的实施增加了政府财政支出。
P1

Eo
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P

Po

图3-6支持价格及结果
Do
So
供给过剩

支持价格的作用可以用农产品支持价格为例来说明：许多经济和自然条件较好的国家，由于农产品过剩，为了克服农业危机，往往采取农产品支持价格政策，以调动农民生产积极性，稳定农业生产。农产品支持价格一般采取两种形式：一种是缓冲库存法，即政府或其代理人按照某种平价收购全部农产品，在供大于求时增加库存或出口，在供小于求时减少库存，以平价进行买卖，从而使农产品价格由于政府的支持而稳定在某一水平上。另一种是稳定基金法，即政府按某种平价收购农产品，在供大于求时维持一定的价格水平，供小于求时使价格不至于过高。但不建立库存，不进行存货调节，在这种情况下，收购农产品的价格是稳定的，同样可以起到支持农业生产的作用。
美国根据平价率来确定支持价格。平价率是指农场主销售农产品所得收入与购买工业品支付的价格之间的比率关系。按平价率来调节农产品的支持价格。法国是建立政府、农场主、消费者代表组成的农产品市场管理组织来制定支持价格。欧共体1963年成立欧洲农业指导委员会和保证基金，用于农产品的收购支出和补贴出口。
供大于求的情况下，如果不使用支持价格政策，将导致这样的结果：一是存货调节。当市场供大于求，价格低时，生产者把部分产品作为库存贮藏起来，不投入市场，从而不形成供给，这就会使供给减少，价格上升。反之，当市场上供给小于需求，价格高时，生产者把原来的库存投入市场，这就在产量无法增加的情况下增加了供给，从而价格下降。这种自发存货调节，对市场的稳定起到作用，但却为投机倒把提供方便。二是地区套利。在现实中，市场往往是地区性的。这样在总体上供求平衡时，也会出现地区性不平衡。这种地区间供求不平衡所引起的价格差就产生了跨地区套利活动。这种活动就是把供大于求，从而价格低的地区的产品运到供小于求，从而价格高的地区。只要这种价格差大于运输费用，这种投机活动就不会停止。这种投机活动有利于市场机制更好地发挥作用，也有利于经济稳定，市场经济本身的一种“内在稳定器internal stabilizer。
支持价格的运用对于经济发展的稳定和制止投机活动有着及其重要的意义。其作用是：第一，稳定生产，减缓经济危机的冲击。第二，通过对不同产业产品的不同的支持价格，可以调节产业结构，使之适应市场变动。第三，实行对农产品生产的支持价格政策，可以扩大农业投资，促进农业劳动生产率的提高。但支持价格会使财政支出增加，政府背上沉重的包袱，降低政府对宏观经济的调节作用。
不论是限制价格还是支持价格，都是政府利用国家机器的力量对商品供求实行的价格管制，限制价格是远远低于均衡价格的商品最高价格，支持价格一般是高于均衡价格的最低价格。前者的长期实行会造成商品持续的严重供不应求，后者的长期实行会造成商品的持续的供过于求，二者都会对市场供求关系的正常实现造成不利的影响，政府为了在实行价格管制的条件下，维持社会稳定，就必须对社会商品供求实行管制，由此就导致经济学上一个基本定理的产生与存在：实行价格管制的国家必然导致对商品供求实行数量管制。

Exercises:
Markets, Demand and Supply
1. The following passage refers to the operation of a free-market economy. Delete the words (in bold) which are incorrect.

In a totally free-market economy, the quantities of each type of good that are bought and sold, and the amounts of factors of production (labour, land and capital) that are used, are determined by the decisions of individual households and firms through the interaction of demand and supply

In goods markets, households are suppliers / demanders and firms are suppliers / demanders. In labour markets, households are suppliers / demanders and firms are suppliers / demanders.

Demand and supply are brought into balance by the effects of changes in price. If supply exceeds demand in any market (a surplus), the price will rise / fall / stay the same. This will lead to a rise in the quantity both demanded and supplied / a fall in the quantity both demanded and supplied / a rise in the quantity demanded but a fall in the quantity supplied / a rise in the quantity supplied but a fall in the quantity demanded. If, however, demand exceeds supply in any market (a shortage), the price will fall / rise / stay the same. This will lead to a fall / rise in the quantity demanded and a fall / rise in the quantity supplied. In either case the adjustment of price will ensure that demand and supply are brought into equilibrium, with any shortage or surplus being eliminated.
2. How will the market demand curve for a 'normal' good shift (i.e. left, right or no shift) in each of the following cases?
a. The price of a substitute good falls. left / right / no shift
b. Population rises. left / right / no shift
c. Tastes shift away from the good. left / right / no shift
d. The price of a complementary good falls. left / right / no shift
e. The good becomes more expensive. left / right / no shift

3. How will the market supply curve of a good shift (i.e. left, right or no shift) in each of the following cases?
a. Costs of producing the good fall. left / right / no shift
b. Alternative products (in supply) become more profitable. left / right / no shift
c. The price of the good rises. left / right / no shift
d. Firms anticipate that the price of the good is about to fall. left / right / no shift

4. How will the following changes affect the market price of wheat flour (assuming that the market is initially in equilibrium)? In each case, sketch what happens to the demand and/or supply curves and, as a result, what happens to the equilibrium price.
a. People consume more bread.

b. The discovery of a new cheaper way of milling flour.

c. The prices of other grains rise.

d. Rice and potatoes fall in price.

5. The diagram below shows the demand for and supply of petrol. The market is initially in equilibrium at point x. There is then a shift in the demand and/or supply curves, with a resulting change in equilibrium price and quantity.

To which equilibrium point (a, b, c, d, e, f, g or h) will the market move from point x after each of the following changes?

a. A rise in the cost of refining petrol.
b. A fall in bus and train fares.
c. A fall in the price of crude oil and an increase in the price of cars.
d. A rise in tax on petrol and a reduction in tax on cars.

6. The demand and supply schedules for wheat in a free market are as follows:
Price per tonne
120
160
200
240
280
320
360
400
Tonnes demanded per week
725
700
675
650
600
550
500
425
Tonnes supplied per week
225
300
400
500
600
750
1000
1300
7.
a. Draw the demand and supply curves on the following diagram:

b. What is the equilibrium price?

c. Suppose the government fixes a maximum price of £200 per tonne What will be the effect?

d. Suppose that supply now increases by 150 tonnes at all prices. Enter the new figues.
Price per tonne
120
160
200
240
280
320
360
400
Tonnes demanded per week
725
700
675
650
600
550
500
425
(old) Tonnes supplied per week
225
300
400
500
600
750
1000
1300
(new) Tonnes supplied per week

e. How much will price change from the original equilibrium (assuming that the government no longer fixes a maximum price)? How much more will be sold?
a. Change in price

b. Change in quantity

教学参考书：
1、孙建锋：《经济学基础》，东北财经大学出版社，2003。
2、徐颂陶：《经济学基础知识》，中国人事出版社，2004。
复习思考题：
梁小民：《西方经济学教学指导书》，中国统计出版社，2002。