第5章成本理论

700 600 500 400 300 200 100 0 80 70 60 50 AC and MC 40 30 20 10 0 1 2 3 4 5 6 Quantity 7 8 9 1 2 3 4 5 6 Quantity 7 8 9
TC
VC FC
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MC
AC AVC
M M' AFC
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Microeconomics
Section 05 Analysis of costs
Definition of Cost
TOTAL REVENUE, TOTAL COST, AND PROFIT
The amount that the firm receives for the sale of its output (cookies) is called its total revenue. The amount that the firm pays to buy inputs (flour, sugar, workers, ovens, etc.) is called its total cost. Profit=Total revenue-Total cost
Variable cost (可变成本)
Variable cost represents expense that vary with the level of output – such as raw materials, wages, and fuel - and includes all costs that are not fixed.
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Definition of Cost
Total cost (总成本)
Total cost represents the lowest total dollar expense needed to produce each level of output Q. TC rises as Q rises.
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Definition of Cost
ECONOMIC PROFIT VERSUS ACCOUNTING PROFIT
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Definition of Cost
生产和成本分别从实物量和价值量角度研究生产问题. 因此,短期成本函数与短期生产函数之间存在密切联系.
M M' AFC
10
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Diminishing Returns and U-shaped Cost Curves
TC P B VC A
TC, VC, MC的 关系,请注意 TC的两个特殊 拐点A,B. AC最低点对应 B点. MC最低点对 应A点. AC, AVC, MC 的关系,注意 D,E ???
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Definition of Cost
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Definition of Cost
The major elements of a firm's cost are its fixed costs (which do not vary at all when output changes) and its variable costs (which increase as output increases). Total costs are equal to fixed plus variable cost: TC=FC+VC
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Definition of Cost
Marginal cost (MC)
The marginal cost of production is the additional cost incurred in producing 1 extra unit of output.
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Definition of Cost
ECONOMIC PROFIT VERSUS ACCOUNTING PROFIT
An economist measures a firm's economic profit as the firm's total revenue minus all the opportunity costs (explicit and implicit) of producing the goods and services sold. Economic profit (经济利润),总收益与总成本之间差额 Normal profit (正常利润),厂商对自己所提供的企业家 才能的报酬支付. An accountant measures the firm's accounting profit as the firm's total revenue minus only the firm's explicit costs.
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Diminishing Returns and U-shaped Cost Curves AC与MC关系
d AC dQ
??
=
d TC TC ′ Q TC 1 TC 1 = = (MC AC ) = TC ′ 2 Q dQ Q Q Q Q
STC (Q ) = Φ(Q ) + b
可变成本 固定成本
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Definition of Cost
在总产量曲线上, 找到每一产量水平相对应的可变 要素劳动的投入量, 再用L去乘已知的价格w, 便可得到每一产量的可变成本. 将产量与可变成本的对应关系描 绘在产量与成本的平面图中,即可 达到总可变成本曲线. 加上固定成本,就得到TC曲线.
TC
TC TVC TFC Q
O
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Definition of Cost
Farmer Smith rents 10 acres of wheat land and employs variable labor. According to the farming production functions, careful use of labor and land allows the inputs and yields shown in columns (1) to (3) of the table. At input price of $5.5 per acre and $5 per worker, we obtain Smith's cost of production shown in column (6). All other cost can be calculated from the total cost data.
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Diminishing Returns and U-shaped Cost Curves
Note how MC intersects AC at its minimum. When MC is below AC, it is pulling AC down. When MC is above AC, it is pulling AC up. When MC just equals AC, AC neither rising nor falling and is at its minimum. Hence, at the bottom of a U-shaped AC, MC=AC=minimum AC. Why???
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Definition of Cost
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Definition of Cost
800
Cost
All cost curves can be derived from the total cost curve
TC is made up of FC and VC. The curve of marginal cost falls and then rises, as indicated by the MC figures given in column (5) of last table.
短期生产函数 劳动价格w和资本价 格r固定. 短期中,资本为固定 投入,L为变动投入, L与产量Q有关.短期 总成本为:
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Q = f L, K
( )
STC = ω L(Q ) + r k
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Definition of Cost
STC = ω L(Q ) + r k
Q的函数,用φ(Q)表示 常数,用b表示
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800 700 600 500 Cost 400 300 200 100 0 80 70 60 50 AC and MC 40 30 20 10 0 1 2 3 4 5 6 Quantity 7 8 9 1 2 3 4 5 6 Quantity 7 8 9
TC
VC FC
10
MC
AC AVC
Definition of Cost
Average cost
Average cost is total cost divided by the total number of units produced.
AC = TC q
Average fixed cost (AFC) Average variable cost (AVC)
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Definition of Cost
Opportunity cost Explicit cost (显性成本) input costs that require an outlay of money by the firm 厂商在生产要素市场上购买或租用他人所拥有的生产要素的实 际支出. 会计学的成本 Implicit cost (隐含成本) input costs that do not require anoutlay of money by the firm 厂商自己拥有的且被用于该企业生产过程的那些要素的总价格. 隐成本也必须从机会成本的角度按照企业自由生产要素在其用 途中所能得到的最高收入来支付,否则,厂商会把自由生产要 素转移出本企业,以获得更高的报酬.
Fixed cost (固定成本)
Fixed cost represents the total dollar expense that is paid out even when no output is produced. Fixed cost is unaffected by any variation in the quantity of output.
FC Q MC P AC E AVC
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Diminishing Returns and U-shaped Cost Curves MC的值是TC和TVC的斜率?
∵ TC (Q ) = TVC (Q ) + TFC dTC dTVC ∴ MC = = +0 dQ dQ
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Diminishing Returns and U-shaped Cost Curves
边际报酬递减规律 Who can tell us ? Then the cost ? In the short run, when factors such as capital are fixed, variable factors show an initial phase of increasing marginal product followed by diminishing marginal product. The corresponding cost curves show an initial phase of declining marginal costs, followed by increasing MC after diminishing returns have set in. 短期生产中,边际产量的递增阶段对应的是边际成本的递减阶段, 边际产量的递减阶段对应的是边际成本的递增阶段,与边际产量 的最大值相对应的是边际成本的最小值.因此,在边际报酬递减 规律下的边际成本MC曲线表现出先降后升的U形特征.