A-Level文科的万金油学科，可以说就是A-Level经济学了，A-Level经济学还是管理类、经济类、营销类、商科类、金融类专业的优势学科，能够有效的提高学生的录取率，几乎所有大学的商科类专业都接受A-Level经济学的成绩。
今天小渊就给各位同学们分享一篇A-Level经济学的笔记：
A-Level经济学总需求和总供给篇-收入的循环流动 The Circular Flow of Income：
This topic is called ‘Aggregate demand and supply. But before we look at these concepts, it is important that you understand the ‘big picture‘.
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 the money that goes out of an economy (leakages or withdrawals).
It allows you to see the ‘general‘ reasons why an economy might grow or shrink in size.
Once you can see the ‘big picture‘ we can then look at the specifics of aggregate demand and aggregate supply.
这部分被称为“总需求和总供应”，在我们了解概念之前，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firms。
In this very simple model of the 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 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 the 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 does emphasise one very important point.
When measuring the size of an economy, or the level of economic activity, 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 ‘rent, wages, profit and income‘ branch represents total income of the economy.
The ‘goods and services‘ branch represents the total output of the economy and the ‘expenditure on goods and services‘ 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 using 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 amount 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 = 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，而公司则从同一种来源借钱进行投资。
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，英国的储蓄率相当低，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，他们对海外项目的投资也是如此。
小渊说：
今天关于A-Level经济学笔记暂时就分享到这里了，喜欢A-Level经济的小伙伴，暑假可以提前预习，打基础哦!
A-Level文科的万金油学科，可以说就是A-Level经济学了，A-Level经济学还是管理类、经济类、营销类、商科类、金融类专业的优势学科，能够有效的提高学生的录取率，几乎所有大学的商科类专业都接受A-Level经济学的成绩。
今天小渊就给各位同学们分享一篇A-Level经济学的笔记：
A-Level经济学总需求和总供给篇-收入的循环流动 The Circular Flow of Income：
This topic is called ‘Aggregate demand and supply. But before we look at these concepts, it is important that you understand the ‘big picture‘.
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 the money that goes out of an economy (leakages or withdrawals).
It allows you to see the ‘general‘ reasons why an economy might grow or shrink in size.
Once you can see the ‘big picture‘ we can then look at the specifics of aggregate demand and aggregate supply.
这部分被称为“总需求和总供应”，在我们了解概念之前，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firms。
In this very simple model of the 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 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 the 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 does emphasise one very important point.
When measuring the size of an economy, or the level of economic activity, 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 ‘rent, wages, profit and income‘ branch represents total income of the economy.
The ‘goods and services‘ branch represents the total output of the economy and the ‘expenditure on goods and services‘ 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 using 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 amount 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 = 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，而公司则从同一种来源借钱进行投资。
In the first diagram, E (Expenditure) = O (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 anymore. 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)= O(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 + I。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：
So we can see that in this 2-sector model, actual investment (the injection) must equal actual saving (the leakage).
It makes sense that the injections should equal withdrawals in equilibrium.
Think of the circular flow diagram as water flowing through pipes, and the ‘households‘ and ‘firms‘ squares as water tanks.
If injections were greater than withdrawals, the amount of water in the system would become infinite, which doesn‘t make sense.
If withdrawals were greater than injections, after a time there would be no water in the system, which also doesn‘t make sense.
所以我们可以看到，在这个 2 部门模型中，实际投资(注入)必须等于实际储蓄(泄漏)。在平衡状态下，注入应该等于退出是有道理的。将圆形流程图想象为流经管道的水，将“家庭”和“公司”方格想象成水箱。如果注入量大于取量量，系统中的水量将变得无限，这是没有意义的。如果提取量大于注射量，那么一段时间后系统中将没有水，这也没有意义。
Although the 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 firms‘ stock levels (which count as investment) will adjust until actual investment (planned investment plus unplanned changes in 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 plans) 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。否则，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 that 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 large.
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，英国的储蓄率相当低，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，他们对海外项目的投资也是如此。
小渊说：
今天关于A-Level经济学笔记暂时就分享到这里了，喜欢A-Level经济的小伙伴，暑假可以提前预习，打基础哦!
