看向世界SpotWorld: Microeconomics微观经济学笔记

Term	Definition
Price elastic of	o Supply-defined as the percentage change in quantity supplied in response to a percentage change in the price of the good. o Demand- defined as the percentage change in quantity in response to a percentage change in the price of the good.
Degree of Elasticity	o Perfectly inelastic(完全无弹性) Ed=0 o Relatively inelastic(缺乏弹性) 0<Ed<1 o Unitary(单一弹性) Ed=1 o Relatively elastic(富含弹性) 1<Ed< ∞ o Perfectly elastic(完全弹性) Ed=∞
Factors of changing in elasticity	o Amount of substitutes o More Substitutes, greater elasticity o Less Substitutes, less elasticity o For example, tea and coffee o Durable of products o Necessary or luxury Product o Number of uses of a goods o Time periods o Longer period of adjustment to a price change the higher the price elasticity of supply Conclusion: o Negative cross elasticity denotes two products that are complements o Positive cross elasticity denotes two products are substitutes
Price Elasticity of Demand Formula	%change in Quantity / %change in price

Supply and Demand

Law of Demand	Price	Quantity	Price	Quantity
Price and quantity have negative relationship	↑	↓	↓	↑
Law of Supply	Price	Quantity	Price	Quantity
Price and quantity have Positive relationship	↑	↑	↓	↓

Utility

Total Utility – Total Satisfaction for all unit of consumption

Marginal Utility – Each satisfaction receives by consumption

Law of Diminishing Marginal Return 边际效用递减法则

· 其他条件不变下，不断投入同一种要素，产量增加到一定值后，产量满足度会递减下降

Resources implement	Total utility (total satisfaction)	Marginal utility (consumption satisfaction)
10	100	100
10	180	80
10	240	60
10	280	40
10	300	20
10	300	0

Types of Profit

· Accounting Profit=Total revenue-explicit cost

· Economic Profit=Total revenue- total opportunity cost (include explicit cost and implicit cost)

Type of Cost

Implicit Cost (隐性成本)

· 是一种隐藏于经济组织总成本之中、游离于财务监督之外的成本

Explicit Cost （显性成本）

· 计入账内的、看得见的实际支出，例如支付的生产费用、工资费用、市场营销费用等

Marginal Physical Product and Marginal Cost

· When the Marginal Physical product curve go down, the marginal cost curve goes up

· When the Marginal Physical product curve go up, the marginal cost curve goes down

Economic of Scale规模经济

· 是指在一定的产量范围内，随着产量的增加，平均成本不断降低的事实

exist when inputs are increased by some percentage and output increases by a greater percentage causing unit cost to fall.

· 规模经济是由于一定的产量范围内，固定成本可以认为变化不大，那么新增的产品就可以分担更多的固定成本，从而使总成本下降。

More changing in variable cost but less influence the fixed cost. As higher productivity once a time, more product to share the same fixed cost and reduce the average cost of each product.

· Inputs Increase (more productivity) in a certain range cause average total cost decrease (more product share fixed cost at the same time)

Input	Output (sales)	Supply (amount of product)	Cost
Normal	High	Increase	Decrease

Diseconomy of Scale 规模不经济

规模不经济是指生产规模扩大时，长期平均成本递增

exist when inputs are increased by some percentage and output increases by a smaller percentage causing the unit cost to rise.

· 当大量程度的输入增加与少量的输出导致成本增加

· Inputs increase (more resources) in a certain range but the output (sales) decrease and cause average total cost increase (less product share fixed cost at the same time)

Input	Output (sales)	Supply (amount of Product)	Cost
Normal	Low	Decrease	increase

The constant return to scale

· 一定量的输入与同等量的输出之间形成的平衡造成成本的维持.

exist when inputs are increased by some percentage and output increases by an equal percentage causing unit cost to remain constant.

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Factors of the economics of scale (decrease the cost):

1. Specialization专业度

2. Learning Effect 学习效应

3. Advance technology 高科技运用

4. Effective resources allocation 有效资源运用

Sunk Cost 沉没成本

· Previous Cost that unable to recover back

· For example, the consumer bought a ticket for the movie but think it was boring, but the ticket payment cannot be recovered, and Consumers need to finish watching it.

For the Perfect competition,

· The seller will face a horizontal demand curve at the equilibrium market price

· This is because of the perfectly competitive the seller sells the homogeneous product, and fewer influences in the perfect market, because it just a price taker in the market. So that he cannot charge higher or lower prices based on the equilibrium price.

Term	Formula
Productive efficient	Marginal Cost= Average cost
Allocative efficient	Marginal Cost=Average Revenue
Marginal Cost Formula	change in Total Cost / Change in Quantity
Marginal Revenue Formula	Change in Total Revenue / Change in Quantity

Term	Definition
Assumptions of the Perfect competition	Each firm produces and sells a homogenous product First have easy entry and exit A large number of buyers and sellers Consumer have perfect information
Price Discrimination	差别取价是一种独占者对同一种产品收取不一样的价格，划分客户，地区等因素，无关成本差别. Price discrimination is the situation where the seller charges different prices for the product it sells, and the price differences do not reflect cost differences. · Perfect Price discrimination · Second Degree Discrimination · Third degree discrimination
Monopolistic competitive	o Facing the horizontal straight-line demand curve o Perfectly elastic o All firm are price taker because sell similar product o Demand curve movement is downward sloping o Because the firm will reduce the price to sell more product.
Characteristics of monopolistic competitive (similar to perfectly competitive)	· Many Producer · Many consumers · Close substitute or Differentiated products · Easier entry and exit · Consumer has a significant preference · Can earn normal profits in the long run