想稳过A2经济考试？市场失灵与经济外部性难点一定要拿下

大家在复习的时候，一个非常重要的环节就是查漏补缺之前新课学习时感到理解很困难的知识点。所以本文就为大家梳理一下A2经济考试2个常见却不好理解的概念——Market Failure 市场失灵和 Externality 经济外部性。

A2经济考试介绍

ALEVEL经济考试试卷分为Paper 1和Paper 2，分别是AS阶段的选择题和大题，占40和60%分值比例。

试卷Paper 3和 Paper 4分别是A2阶段的选择题和大题，分别占35%和65%的分值比例。

ALEVEL经济大题的难点和重点都是essay，分值大概占50%以上。

A2经济考试复习重要概念讲解：

市场失灵

01

Reasons for market failure 

市场失灵的原因

1. Market failure occurs whenever a market leads to a misallocation of resources.
2. A misallocation of resources is when resources are not allocated to the best interests of society. There could be more output in the form of goods and services if the resources were used in a different way.
3. Economic and social welfare is not maximised where there is market failure.

02

Types of market failure

市场失灵的种类

o ExternalitiesAn externality is the cost or benefit a third party receives from an economic transaction outside of the market mechanism. In other words, it is the spillover effect of the production or consumption of a good or service. 
Negative externalities are caused by the consumption of demerit goods, such as cigarettes, and positive externalities are caused by the consumption of merit goods, such as recycling schemes.
o The under-provision of public goodsPublic goods are non-excludable and non-rival, and they are underprovided in a free market because of the free-rider problem.
o Information gapsIt is assumed that consumers and producers have perfect information when making economic decisions. However, this is rarely the case, and this imperfect information leads to a misallocation of resources.
o MonopoliesSince the consumer has very little choice where to buy the goods and services ed by a monopoly, they are often overcharged. This leads to the underconsumption of the good or service, and therefore there is a misallocation of resources, since consumer needs and wants are not fully met.
o Inequalities in the distribution of income and wealthThere is an unequitable distribution in income and wealth. Income refers to a flow of money, whilst wealth refers to a stock of assets. This can lead to negative externalities, such as social unrest.

A2经济考试复习重要概念讲解：

经济外部性

An externality is the cost or benefit a third party receives from an economic transaction outside of the market mechanism. In other words, it is the spill-over effect of the production or consumption of a good or service.
Externalities can be positive (external benefits) or negative (external costs).
Negative externalities are caused by demerit goods. These are associated with information failure, since consumers are not aware of the long run implications of consuming the good, and they are usually overprovided. For example, cigarettes and alcohol are demerit goods.The negative externality to third parties of consuming cigarettes is second-hand smoke or passive smoking.
Positive externalities are caused by merit goods. These are associated with information failure too, because consumers do not realise the long run benefits to consuming the good. They are underprovided in a free market. For example, education and healthcare are merit goods. The positive externality to third parties of education is a higher skilled workforce. 
The extent to which the market fails involves a value judgement, so it is hard to determine what the monetary value of an externality is. For example, it is hard to decide what the cost of pollution to society is. Different individuals will put a different value on it, depending on their own experiences with pollution, such as how polluted their home town is. This makes determining government policies difficult, too.

最后提醒一下同学们，虽然AQA今年已经官宣全球ALEVEL考试取消，但其实不论2021 A2经济考试和其他考试取不取消，复习都是少不了的。因为今年的替代方案，导师评估打分不同于去年的预估打分，最终出分都是需要“证据”支持的，包括但不限于平时作业、测试、模考、外部试卷等考察。

所以，同学们，特别是“考试型选手”不仅要保持和大考正常开考时一样的学习状态，也要有意识地进阶自己的平时成绩。

如果你觉得兼顾日常学习与大考太难，点击预约试听【橡沐ALEVEL同步培训班】，全球海归授课，紧贴考试局新政策，根据不同考试局整理高频考察点，提前攻克薄弱环节，无论考试规则怎样变化，都能助力稳定A*实力。

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