【5月AP备考】微观经济学知识点总结：Deadweight Loss

AP, 国际课程 March 22, 2018

A．What is deadweight loss? （定义）

Deadweight Loss （无谓损失），又称为福利净损失（Welfare Loss），是指由于市场未处于最优运行状态（Market Equilibrium）而引起的社会成本。所产生的社会福利损失具体体现在消费者剩余（Consumer Surplus）和生产者剩余（Producer Surplus）的减少。

B．Why it is so important?（相关考题）

Deadweight Loss是一个相对抽象的概念，并和许多知识点存在联系。在历年的AP考试当中，这个知识点却是一个必不可少的考点。以下是历年真题当中出现过与Deadweight Loss相关的考题，大家看完这篇文章之后，不妨做一下真题，有不懂的问题欢迎在AP群里面提出，和同学们老师们一起探讨。

·与Deadweight Loss相关的Multiple-Choice Questions

Ø (2010) Q3&4

Ø (2015) Q57

Ø (2012) Q48

·与Deadweight Loss相关的 Free-Response Questions

Ø (2018) Q1

Ø (2015) Q2

Ø (2014) Q1

Ø (2012) Q1

C．What may cause deadweight loss?

1. A Binding Price (Price Floor & Price Ceiling)

• Price CeilingsØDefinition:A price ceiling is meant to set a price below the equilibrium.

Ø Example: Rent Control

Ø Welfare Analysis (measure the deadweight loss)

• Price Floors

Ø A price floor is meant to set a price above the equilibrium.

Ø Example: Minimum Wage

Ø Welfare Analysis (measure the deadweight loss)

2. A Tax or Subsidy

· TaxØ Tax: Market Outcome

Ø Welfare Analysis (measure the deadweight loss)

· Subsidy

Ø Subsidy: Market Outcome

Ø Welfare Analysis (measure the deadweight loss)

3. Externality

· Positive ExternalityØ Positive Externality: Market Outcome

Ø Welfare Analysis (measure the deadweight loss)

· Negative Externality

Ø Negative Externality: Market Outcome

Ø Welfare Analysis (measure the deadweight loss)

4. Artificial Scarcity as a Result of Monopoly Pricing

Ø Monopoly’s market outcome and prefect competition market outcome compared

Ø Welfare Analysis (measure the deadweight loss)

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