CH 7
• Cost and cost Minimization
Preview
• 1. economic cost ~opportunity cost
• 2. sunk and nonsunk cost
• 3. Short run cost :
Fixed cost, variable cost and nonsunl cost
• 4. Long run cost minimization :
Explicit and implicit costs
• What is the cost to an airline of using one of its planes in scheduled passenger service ?
• Explicit costs: fuel, crew salaries , maintenance, airport fees, food, drinks
• Implicit costs: 放棄的租金
機會成本• The value of the next best alternative that is
forgone when another alterative is chosen
• 店要關門大吉 ?
• 繼續經營的花費 =100,000( 勞工 )
+80,000( 原料 )
+ 您的投入 ( 包括勞動與資金 ) 的機會成本(75,000)=255,000
機會成本 (looking forward)
• Forward looking • It measures the value that the decision maker sacrificed at
the time the decision is made and beyond • 汽車廠已購入鋼片 (sheet steel) = 存貨價值 =1,000,000• 這些剛片可以用於製造汽車或是出售• 若出售 , 可賣 1,200,000• 用於製造汽車的機會成本 ?• =1,200,000( 決策制定時放棄的價值 ) 不等於會計成本
1,000,000
會計與經濟學的橋樑 : 財管
• 第35號公報• 第10號公報• 員工入股分紅
Also depends on the decision being made
• 還沒買鋼時 , 買鋼的機會成本 =?
• 1,000,000
讀碩專的機會成本 =?
• 讀碩專的成本 =
1. 學費的機會成本2. 時間價值的機會成本3. ,……whatelses
~ 上碩專課壓力較大 ,
~ 教大學部血壓較高
• 讀博士的成本 :
Accounting costs and economic costs
• Accounting costs: the total of explicit costs that have been incurred in the past
To serve an audience outside the firm
• Economic costs: the sum of the firm’s explicit costs and implicit costs
• 開店預估營收 < economic cost: 不開
短期成本分析• 1. fixed costs and variable costs
• 2. fixed costs :sunk costs and nonsunk costs
Sunk cost vs nonsunk cost
• Sunk costs: costs that have already been incurred and cannot be recovered
• Nonsunk costs: costs that are incurred only if a particular decision is made
• Example: 買電影票看電影 , 不好看 , 電影票已經買了 , cannot be recovered
• 但是你可以提前離場 , 省去時間成本 (nonsunk costs)
Sunk and nonsunk fixed costs
• 海角七號 : 不賣座 , 劇本的剩餘價值 =?
• 不要廣告了 :
Sunk costs and nonsunk costs
• Example : 已繳學費 = 學雜費 + 學分費• 何者是 sunk costs, nonsunk costs,
• 食之無味 , 棄之可惜 !~ 套牢
Sunk costs and nonsunk costs
• Example : 保齡球工廠 (specified that it has no alterative uses) 專屬 , 投資需 500 萬
• In deciding whether to build the factory, 500 萬 is a non sunk cost
• After the factory is built, 500 萬 is a sunk cost• 專屬投資的產業 , 比較會導致激烈競爭 , because Exit cost is high ! 如 DRAM, TFT-LCD
Sunk cost vs fixed cost
• Fixed costs 與 variable costs 是短期的概念• Fixed and sunk costs : output insensitive and
unavoidable, even if the firm produces zero output: 例如 , 只有特定用途的專屬設備
• 買了電影票 , 看到一半 , 很難看 , 這票還有其他使用價值 ?
• Fixed and nonsunk costs: outputs insensitive, but avoidable if the firm produces zero output. 例如 , 教室的電費 , 或是有人願意買或承租的設備
• 只有一名 , 上課要不要開燈 ? 2名 , 3,….
Quiz 0324
• What mistakes Sparky did in his late career ?
Variable cost vs fixed cost
• 只有一名乘客 , 航班要不要飛 : 要• 油料成本就是 nonsunk cost, 餐點就是 variable
cost• 當有兩名時 , nonsunk cost 一樣 , 但是總變動
成本增加• Fixed costs 與 variable costs 是短期的概念• Variable costs: 一定是 nonsunk? Output
sensitive, 例如 labor, materials • Fixed costs: the cost of fixed inputs: it does not
vary with output
FIGURE 7-13 Classifying Inputs and Costs in the Short Run
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-13
帳戶管理費要收 ?
• 1. 有話好説?
• 2. 電子報• 3. 不能加入存保 ?
Long run cost minimization
Cost minimization
• Long run: the period of time that is long enough for the firm to vary the quantities of all of its inputs as much as it desires
• Short run : the period of time in which at least one of the firm’s input quantities cannot be changed
Long run cost minimization
長期成本函數QrwrKQrwwLrwQC
長期要素需求QrwKQrwL
QKLFtosubject
wLrKKL
),,(*),,(*),;(
),,(*),,,(*
),(:
min,
• 找 最低成本線 such that
• 在等產量線上
FIGURE 7-1 Isocost Lines
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-01
FIGURE 7-1 Isocost Lines
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-01
FIGURE 7-2 Cost-Minimizing Input Combination
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-02
經濟涵義
出K花在 K每在 每一元的出L花在 L每在 每一元的r
MP
w
MP
r
w
MP
MP
L
KMRTS
等成本線斜率等產產量線斜
KL
K
LLK
角解
FIGURE 7-3 Corner-Point Solution to theCost-Minimization Problem
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-03
比較靜態• 要素價格改變• 產量改變
FIGURE 7-5 Comparative Statics Analysis of Cost-Minimization Problem with Respect to the Price of Labor
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-05
CASE
• Supertanker 1, 2
• Offshoring cost
FIGURE 7-6 Comparative Statics Analysis of the Cost-Minimization Problem with Respect to the Price of Labor for a
Fixed-Proportions Production Function
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-06
FIGURE 7-8 Comparative Statics Analysis of Cost-Minimization Problem with Respect to Quantity: Normal Inputs
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-08
FIGURE 7-9 Comparative Statics Analysis of Cost-Minimization Problem with Respect to Quantity: Labor is an Inferior Input
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-09
FIGURE 7-10 Burke Mills Revisited
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-10
要素需求
FIGURE 7-11 Labor Demand Curve
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-11
要素需求價格彈性
r
rK
K
w
wL
L
rKwL
,, ,
FIGURE 7-12 The Price Elasticity of Demand for Labor Depends on the Elasticity of Substitution Between Labor and Capital
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-12
(Figure continues on next slide)
FIGURE 7-12 (Continued)
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-12
Short-run Cost minimization
短期成本函數KrQKwLKrwQC
短期要素需求QKL
QKKLFtosubject
wLKrL
),(*),,;(
),(*
),(:
min
FIGURE 7-13 Classifying Inputs and Costs in the Short Run
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-13
FIGURE 7-14 Short-run Cost Minimization with One Variable Input
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-14
• F點 ( 短期 )比 A點 ( 長期 ) 成本高
FIGURE 7-15 Short-run Input Demand versus Long-runInput Demand
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-15
FIGURE 7-16 Short-Run Cost Minimizing Input Combination with Two Variable Inputs
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 7, Figure 07-16
More than one variable input with one fixed input
ISOQUANTQKKMLFtosubject
mMwLKrL
~),,(:
min