View
262
Download
1
Embed Size (px)
Citation preview
長期成本
Long run cost minimization
長期成本函數QrwrKQrwwLrwQC
長期要素需求QrwKQrwL
QKLFtosubject
wLrKKL
),,(*),,(*),;(
),,(*),,,(*
),(:
min,
邊學邊做 8.1
長期成本函數QwrQrwrKQrwwLrwQC
r
wQQrwK
w
rQQrwL
Qr
wLL
r
wLK
r
w
L
K
KL
KL
MP
MPMRTS
QKLLKKLFtosubject
wLrK
K
LLK
KL
25),,(*),,(*),;(
)50
(),,(*,)50
(),,(*
)(50
,*
25
25
5050),(:
min
2/12/1
2/12/1
2/12/1
2/12/1
,
FIGURE 8-2 Long-Run Total Cost Curve for Learning-By-Doing Exercise 8.1
W=25, r=100
FIGURE 8-1 Cost Minimization and the Long-Run Total Cost Curve for a Producer of Television Sets
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-01
(Figure continues on next slide)
FIGURE 8-1 (Continued)
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-01 continued
How does the long-run total cost curve shift when input prices
change?• Just one input price changes
• All input prices change proportionately
FIGURE 8-3 How a Change in the Price of Capital Affects the Optimal Input Combination and Long-Run Total Cost for a Producer
of Television Sets
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-03
FIGURE 8-4 How a Change in the Price of Capital Affects the Long-Run Total Cost Curve for a Producer of Television Sets
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-04
FIGURE 8-5 How a Proportionate Change in the Prices of All Inputs Affects the Cost-Minimizing Input Combination
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-05
Application 8.1
• The long-run cost of Trucking , 2
FIGURE 8-6 Long-Run Total Cost Curve for a Trucking Firm
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-06
FIGURE 8-7 Deriving Average and Marginal Cost from theTotal Cost Curve
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-07
(Figure continues on next slide)
FIGURE 8-7 (Continued)
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-07 continued
FIGURE 8-9 Relationship Between the Average andMarginal Cost Curves
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-09
長期平均成本與邊際成本
)(25
)(
25),,(*),,(*),;(
QMCwr
QAC
長期成本函數
QwrQrwrKQrwwLrwQC
FIGURE 8-8 Long-Run Average and Marginal Cost Curves for Learning-By-Doing Exercise 8.2
W=25, r=100
FIGURE 8-10 The Average and Marginal Cost Curves for University Education at U.S. Universities
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-10
Quiz (0331)
• In the study of Rajindar and Manjulika Koshal (1005) how school size affects the average and marginal cost of higher education ?
• 為何大學的邊際成本遞減 ?
• 學生增加 , 圖書館會增蓋 ?
• 範例 8.2 中提到學校額外增加一名學生的邊際成本會低於位學生的平均成本,因此增加學生人數可以降低學生的平均成本,如果是這樣為何碩士在職專班人數只有 20 人一班,似乎有些規模不經濟,是否應該要增加成一班至少 30-40 人,降低平均成本 !
Economies of scale
• Economies of scale :
average cost decreases as output goes up
• diseconomies of scale :
average cost increases as output goes up
Causes of economies of scale
• Increasing returns to scale
• Indivisible inputs available only in a certain
minimum size. Its quantity cannot be scaled down as the firm’s output goes to zero
生產線機器 就長期考慮也是需要最小的設備規模• Specialization of labor
Causes of diseconomies of scale
• decreasing returns to scale• Managerial diseconomies : a given percentage
increase in output forces the firm to increases its spending on the services of the managers by more than this percentage
• Key individual’s contribution cannot be replicated
• 宏碁 vs 華碩
FIGURE 8-11 實證研究結果 :Real-World Average Cost Curve
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-11
MES
• MES: minimum efficient scale :
the smallest quantity at which the long run average cost curve attains it minimum point
• MES and industry structure : 表 8.1 p276
• MES 愈大表示 : 市場愈不競爭
Economies of scale and returns to scale
• Increasing returns to scale : economies of scale
• decreasing returns to scale : diseconomies of scale
• 表 8.3 (p277) 自行練習
Application 8.2
• The costs of higher education, 2
Application 8.3
• Economies of Scale in Refining Alumina
Application 8.4
• 為何而併 ?
• Economies of scale or
• Reduce competition
FIGURE 8-12 醫院合併 Average Cost Curves for “Backoffice 後勤” Activities
in a Hospital
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-12
Measure the extent of economies of scale ~ 表 8.5
1
1
)(
)(
,
,
,
QTC
QTC
QTC
ACMC
ACMC
QAC
QMC
QTC
QTC
QQTC
TC
短期成本
L
L
MP
w
Q
wQL
Q
QTVC
Q
QSTCQSMC
AP
w
Q
wQL
Q
QTVCQAVC
Q
QSTCQSAC
TFCQTVCQSTC
)()()()(
*)()()(
)()(
)()(
FIGURE 8-16 Short-Run Marginal and Average Cost Curves
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-16
FIGURE 8-13 Short-Run Total Cost Curve
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-13
短期成本與長期成本
)();( 1 QTCKQSTC
FIGURE 8-14 Why Total Costs Are Higher in the Short Runthan in the Long Run
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-14
FIGURE 8-15 Relationship Between Short-Run and Long-RunTotal Cost Curves
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-15
FIGURE 8-17 The Long-Run Average Cost Curve as anEnvelope Curve
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-17
FIGURE 8-18 The Relationship Between the Long-Run Average and Marginal Cost Curves and the Short-Run Average and
Marginal Cost Curves
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-18
短期最適化 : 邊學邊做 8.4~ 圖8.19
:w=25, r=100
KrQTFC
K
QwQTVC
短期成本函數KrK
QwKrQKwLrwQSTC
K
QQKL
QKLLFtosubject
wLKrKL
)(
2500)(
2500),(*),;(
2500),(*
50),(:
min
2
2
2
2/12/1
1,
Application 8.5
• Tracking Railroad Costs, 2, 3
• BDT(1984)(JIE)
Quiz (0421)
• Why did US shipping freight by the train in the 1990s take longer than it have 30 years earlier ?
FIGURE 8-20 Long-Run and Short-Run Average Cost Curvesfor a Railroad
Besanko & Braeutigam/Microeconomics: An Integrated ApproachChapter 8, Figure 08-20
Economies of scope
)0,0(),0()0,(),(
),0()0,(),(
2121
2121
TCQTCQTCQQTC
QTCQTCQQTC
例子• 範疇經濟也就是多樣化經濟,即企業在
生產不同的產品時,若出現成本遞減的現象,則就可稱之為範疇經濟。例如聯合報系在出刊報合報以後,還可以利用同樣的印報機器來出刊民生報、聯合晚報,此即範疇經濟的表現;此外,美語補習班除了教美語以外,還可代辦申請赴美念書或辦理旅遊等等。
Reasons
• A firm’s ability to use a common input to make and sell more than one output
• ~ 金控的範疇經濟
Application 8.6
• Economies of Scope for the Swoosh , 2
• Swoosh
Economies of experience
• Cost advantages that result from accumulated experience
• Learning by doing
• Experience curve : a relationship between average variable costs and cumulative production volume
• Why not “average fixed costs?”
Economies of scale and economies of experience
• 排課 : 9 學分都教個體 ~economies of scale
• 一直都教個體 : 累積經驗 ~ economies of experience
• 製程改善 ,….
Experience elasticity
BAN
ABN
NNAVC
NNAVC
NN
NAVCNAVC
ANNAVC
B
B
B
1
1
)(
)()(
)(
)(
SLOPE OF the experience curve
)(
)2(
2)2(
)(
)2(
NAVC
NAVCB
AN
NA
NAVC
NAVC BB
B
FIGURE 8-21 Experience Curves with Different Slopes
Application 8.7
• Experience Reduces Costs of Computer Chips
Estimating cost functions
• Total cost function
),,( rwQTC
How to estimate cost functions?
• 1. cross-section data
Estimating cost functionsconstant elasticity cost function
(CECF)
rdwcQbaTC
bwhere
rwaQwrQTC
QTC
dcb
lnlnlnlnln
),,(
,
Why constant ?
brwaQ
rwabQ
QAC
QMC
QTC
QTC
QQTC
TC
rwaQwrQTC
dcb
dcb
QTC
dcb
1
1
, )(
)(
),,(
Problems of CECF
• Does not allow for the possibility of AC(Q) that first decreases and then increases as Q increases
Estimating cost functionstranlog cost function
fucntionstofformgeneral
rwb
rbwbQb
rbwbQbaTC
CURVECOSTSHAPEU
cos`
,...))(ln(ln
)(ln)(ln)(ln
lnlnlnlnln
7
26
25
24
321
Translog cost function
• 碩博士論文