A-Level经济学习笔记：总需求和总供给篇-收入的循环流动

1、A-Level经济学习笔记:总需求和总供给篇-收入的循环流动This topic is called 1 Aggregate demand and supply. But before we look at these concepts, it is important that you understand the f big picture1.The circular flow of income is a good place to start.It shows all of the money coming into an economy (injections) and all of

2、 the money that goes out of an economy (leakages or withdrawals).It allows you to see the 1 general1 reasons why an economy might grow or shrink in size.Once you can see the 1 big picture1 we can then look at the specifics of aggregate demand and aggregate supply.这局部被称为“总需求和总供应。在我们了解概念之前,Although th

3、e amount that households plan to save may not be the same as the amount that firms plan to invest, the actual amounts are always equal.If the plans are not the same, the firms1 stock levels (which count as investment) will adjust until actual investment (planned investment plus unplanned changes in

4、the stock level) equals actual saving.Of course, the economy is only in an equilibrium position if the plans are the same.Otherwise, firms will find their stocks build up (or disappear) and change their output levels accordingly to allow for the different saving plans (and, therefore, consumption pl

5、ans) of the households.尽管家庭计划储蓄的金额可能与公司计划投资的金额 不同，但实际金额总是相等的。如果计划不同，公司的存量水平(计为投资)将调整, 直到实际投资(计划投资加上存量水平的计划外变化)等于 实际储蓄。当然，只有在计划相同的情况下，经济才会处于 均衡状态。否那么，公司会发现他们的库存增加(或消失)并相应地改变他们的产出水平，以适应家庭的不同储蓄计划 （因此，消费计划）。It does make sense that savings equals investment. In most economies in the world, the amount tha

6、t is invested over the long term is closely related tothe amount that the economy saves.The UK traditionally has quite a low savings ratio, especially when the economy is doing well, and this has been translated into a poor record on investment over the years.In Japan, the savings ration is very lar

7、ge.Investment is also high in Japan, as is their investment in projects abroad.储蓄等于投资是有道理的。在世界上大多数经济体中,长期投资的金额与经济体的储蓄金额密切相关。传统上，英的储蓄率相当低，尤其是在经济表现良好的情况下，这已 转化为多年来的投资记录不佳。在日本，储蓄率非常大。日 本的投资也很高，他们对海外工程的投资也是如此。需要有“大局观”。收入的循环流动是一个很好的起点。它显 示了进入经济体的所有资金（注入）和流出经济体的所有资 金（泄漏或取款）。它使您可以了解经济规模可能增长或缩 小的“一般”原因。一旦您看

8、到“大图”，我们就可以查看总需 求和总供给的细节。The 2-sector model让我们从最简单的模型开始。假定经济仅由以下两个部 门组成：家庭households和企业firmsRENT WAGES PROFIT .ANDINTEREST(INCOME)RENT WAGES PROFIT .ANDINTEREST(INCOME)HOUSEHOLDSLANDLABOURCAPITAL1GOODSANDSERVICES(OUTPUT)EXPENDITUREON GOODSAND SERVICES(EXPENDITURE)FIRMSIn this very simple model of th

9、e whole economy, it is assumed that the households own all the factors of production.They sell these factors to the firms, earning rent on their land, wages for the use of their labour, and profit and interest for the use of their capital.This is shown on the left hand side of the diagram.The green

10、line shows the factors of production going from the households to the firms and the red line shows the money payments by the firms for these factors going back to the households.在整个经济的这个非常简单的模型中，假设家庭拥有所 有的生产要素。他们将这些要素卖给企业，在他们的土地上 赚取租金，为使用他们的劳动赚取工资，为使用他们的资本 赚取利润和利息。这显示在图表的左侧。绿线表示生产要素从家庭流向企业，红线表示企业为这些

11、要素流向家庭的货币支付。The firms then use these factors to produce goods and services. And who buys these goods and services?The households, of course, using the income they earned from the sale of their factors.This is shown on the right hand side of the diagram.Again, the green line represents movements of t

12、he physical and the red line shows the movement of the money.然后，这些公司利用这些因素来生产商品和服务。谁购 买这些商品和服务？当然，这些家庭使用他们从出售他们的 要素中获得的收入。这显示在图表的右侧。同样，绿线代表 实物的走势，红线代表货币的走势。Although this model is very simple, it doesemphasise one very important point.When measuring the size of an economy, or the level of economic ac

13、tivity, there are three ways of doing it.In the diagram above you can see that three of the four moving lines have also been labelled in black. The f rent, wages, profit and income1 branch represents total income of the economy.The r goods and services1 branch represents the total output of the econ

14、omy and the 1 expenditure on goods and services1 branch represents the total expenditure of the economy.虽然这个模型很简单，但它确实强调了一个非常重要的 点。在衡量一个经济体的规模或经济活动的水平时，可以通 过三种方式来衡量。在上图中，您可以看到四条移动线中的 三条也被标记为黑色。“租金、工资、利润和收入分支代表 经济的总收入。“商品和服务”部门代表经济的总产出，“商品 和服务支出部门代表经济的总支出。So the size of an economy can be measured usi

15、ng either the income, output or expenditure method.Notice that the three methods should give exactly the same answer. It is fairly obvious that the amount of money spent must equal the value of the goods and services that this money is spent on.Although less obvious, it should make sense that the am

16、ount of money spent will equal the income of the spenders, assuming that none of this income is saved.This brings us to another key point. There are no injections into this circularflow and no leakages from the circular flow (like saving) at this stage. Hence, Income = Output = Expenditure.因此，一个经济体的

17、规模可以使用收入、产出或支出方 法来衡量。请注意，这三种方法应该给出完全相同的答案。 很明显，花费的金额必须等于所花费的商品和服务的价值。 虽然不那么明显，但假设这些收入都没有被储蓄，那么花费 的金额将等于支出者的收入应该是有意义的。这给我们带来 了另一个关键点。在这个阶段，没有注入到这个循环流中， 也没有从循环流中泄漏(如储蓄)。因此，收入=产出二支 出。Including leakages and injections在这个简单的模型中，到目前为止，我们假设系统是完 全封闭的。不过，可以公平地假设，家庭不会花掉他们所有 的收入，而且公司有时会投资于新资本。上图将第一个循环流程图更进一步。两

18、条蓝线表示储蓄 从经济中流出和投资注入经济。储蓄漏水到哪里去，投资注 入从哪里来？简而言之，储蓄存入银行部门或资本市场，而 公司那么从同一种来源借钱进行投资。In the first diagram, E (Expenditure) = 0 (Output)=Y (Income).Now there are two types of expenditure： consumption (by households) and investment (by firms), So E = C + I.Also, the households?income is not all spent anymor

19、e. Some of it is saved, so Y = C + S.We know that in equilibrium, Y = E, so by substituting we have：在第一个图中，E (支出)二0 (产出)=Y (收入)。现 在有两种支出：消费(家庭)和投资(企业)，所以E=C + Io还有，家庭？收入不再全部花掉。其中一些被保存，所 以Y=C + S。我们知道在平衡状态下，Y = E,所以通过 代入我们有：Y= EC + S = C + IS= I (by cancelling out the Cs)So we can see that in this 2-sector model, actual investment (the injection) must equal actu