曼昆微观经济学ch13

Profit is the firm’s total revenue minus its total
cost.
Profit = Total revenue – Total cost
the amount a firm receives from the sale of its output
the market value of the inputs a firm uses in production
As more and more workers are hired at a firm,
each additional worker contributes less and less to production because the firm has a limited amount of equipment.
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The Production Function
A production function shows the
relationship between the quantity of inputs used to produce a good and the quantity of output of that good.
The explicit cost? Implicit cost? Opportunity cost?
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Economic Profit vs. Accounting Profit
Economists measure a firm’s economic profit as
Marginal Product The marginal product of any input in the
production process is the increase in output arising from an additional unit of that input.
worker might have higher marginal product than the first because a team of workers can divide tasks and work more productively than a single worker.
Such firms would first experience increasing
In addition, it will introduce you to a part of
economics called industrial organization- the study of how firm’s decisions about prices and quantities depend on the market conditions they face.
工人 数量 0
1 2
产量
0 50 90
劳动的边 际产量
50 40
工厂 成本 30
30 30
工人 成本 0
10 20
总成本
30 40 50
3
4 5
120
140 150
30 20 10
30
30 30
30
40 50
60
70 80
总成本
$80 70 60 50 40 30 20 10
TC TC (Q )
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糕点产量
150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 1 2 3 4 5
生产函数
Fra Baidu bibliotek
雇佣的工人数量
Yet actual firms are often a bit more complicated
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Economists versus Accountants
Economic profit is smaller than accounting profit.
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Quick Quiz
Farmer McDonald gives banjo lessons for $20 an
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The slope of the production function
measures the marginal product of a worker. As the number of workers increases, the marginal product declines, and the production function becomes flatter.
than this.
In many firms, diminishing marginal product does not
start to occur immediately after the first worker is hired.
Depending on the production process, the second or third
Explicit Costs and Implicit Costs Explicit costs are input costs that require an
outlay of money by the firm.
Implicit costs are input costs that do not require
marginal product for a while before diminishing marginal product sets in.
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From the Production Function to the Total-Cost Curve
© 2009 South-Western, a part of Cengage Learning, all rights reserved
We used the supply curve to summarize firm’s
production decisions. For analyzing many questions, the law of supply is all you need to know about firm behavior. We now examine what decisions lie behind the supply curve.
hour. One day, he spends 10 hours planting $100 worth of seeds on his farm.
What opportunity cost has he incurred? What
cost would his accountant measure?
an outlay of money by the firm.
A firm’s cost of production include explicit costs
and implicit costs.
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Costs as Opportunity Costs
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Costs as Opportunity Costs
A firm’s costs of production includes all the
opportunity cost of making its output of goods and services.
For instance, that Helen used $300,000 of her
savings to buy her cookie factory from the previous owner. If Helen had instead left this money deposited in a savings account that pays an interest rate of 5 percent, she would have earned $15,000 per year.
工人 数量 0 1 2 3
总成本函数
产量 0 50 90 120
工厂 成本 30 30 30 30
工人 成本 0 10 20 30
总成 本 30 40 50 60
4
5
10 20 30 40 50 60 70
If these seeds will yield $200 worth of crops,
does McDonald earn an accounting profit? Does he earn an economic profit?
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Production and Costs
total revenue minus total cost, including both explicit and implicit costs.
Accountants measure the accounting profit as
the firm’s total revenue minus only the firm’s explicit costs.
Q=f(L,K)
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工人 数量 0
1 2
产量
0 50 90
劳动的边 际产量
50 40
工厂 成本 30
30 30
工人 成本 0
10 20
总成本
30 40 50
3
4 5
120
140 150
30 20 10
30
30 30
30
40 50
60
70 80
糕点产量
We assume that the size of factory is fixed
and we can vary the quantity of goods produced only by changing the number of workers. This assumption is realistic in the short run, but not in the long run.
5 Firm Behavior and the Organization of Industry
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CHAPTER
13
The Costs of Production
Economics
PRINCIPLES OF
N. Gregory Mankiw
bannannan@dufe.edu.cn 2015-05-21
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What Are Costs?
The firm’s objective
The economic goal of the firm is to
maximize profits.
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Total Revenue, Total Cost, Profit
TPL Q f ( L， K )
生产函数
工人数量 0 1 2 产量 0 50 90
150 140 130 120 110 100 90 80 70 60 50 40 30 20 10 0 1 2 3 4 5
3
4 5
120
140 150
雇佣的工人数量
The Production Function
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The Production Function
Diminishing Marginal Product Diminishing marginal product is the property
whereby the marginal product of an input declines as the quantity of the input increases.