McGraw-Hill/Irwin Copyright © 2009 by The McGraw-Hill Companies, Inc. All rights reserved.

The Costs ofProduction

Chapter 8

Chapter Objectives

• Explicit and implicit costs• Law of diminishing returns• Fixed and variable costs• Total, average, and marginal

costs• The firm’s size in the long run

8-2

Economic Costs

• Opportunity costs• Explicit + implicit costs• Explicit costs

–Monetary payments• Implicit costs

–Value of next best use–Self-owned resources–Self-employed resources

8-3

Profit

• Accounting profit–Total revenue less explicit cost

• Economic or pure profit–Total revenue less economic cost

8-4

Profits Compared

EconomicProfit

AccountingCosts (Explicit

Costs Only)

AccountingProfit

ExplicitCosts

Implicit Costs(Including a

Normal Profit)

Econ

omic

(Opp

ortu

nity

)C

osts

Tota

l Rev

enue

Economic Accounting

8-5

Short and Long Run

• The short run–Fixed plant capacity–Variable intensity of plant use–Variable output

• The long run –Variable plant capacity–Firms enter and exit

8-6

Production Relationships

• Total product (TP)• Marginal product (MP)

• Average product (AP)

Average Product Total ProductUnits of Labor=

Marginal Product Change in Total ProductChange in Labor Input=

8-7

Law of Diminishing Returns

• Fixed technology• Add variable resource to fixed

resource• Marginal product will decline

–Beyond some point• Rationale

8-8

Law of Diminishing Returns

(1)Units of the

Variable Resource(Labor)

(2)Total Product

(TP)

(3)Marginal Product

(MP),Change in (2)/Change in (1)

(3)AverageProduct

(AP),(2)/(1)

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01025456070757570

-10.0012.50

]]]]]]]]

8-9

1015

IncreasingMarginalReturns

IncreasingMarginalReturns

Law of Diminishing Returns

(1)Units of the

Variable Resource(Labor)

(2)Total Product

(TP)

(3)Marginal Product

(MP),Change in (2)/Change in (1)

(3)AverageProduct

(AP),(2)/(1)

012345678

01025456070757570

101520151050

-5

-10.0012.5015.0015.0014.0012.5010.718.75

]]]]]]]]

DiminishingMarginalReturns

NegativeMarginalReturns

8-10

0

10

20

30

Tota

l Pro

duct

, TP

1 2 3 4 5 6 7 8 9

20

10

Mar

gina

l Pro

duct

, MP

1 2 3 4 5 6 7 8 9

TP

MP

AP

IncreasingMarginalReturns

DiminishingMarginalReturns

NegativeMarginalReturns

Law of Diminishing Returns

8-11

Law of Diminishing Returns

Short-Run Production Costs

• Fixed Costs–Do not vary with output

• Variable Costs–Materials, most labor

• Total Cost–TC = TFC + TVC

8-13

Per-Unit Production Costs

• Average fixed cost AFC = TFC/Q

• Average variable costAVC = TVC/Q

• Average total cost ATC = TC/Q = TFC/Q + TVC/QATC = AFC+AVC

• Marginal costMC = change in TC/change in Q

8-14

Cost for Individual Firm

Short-Run Production Costs

Cos

ts

1 2 3 4 5 6 7 8 9 100 Q

100

200

300

400

500

600

700

800

900

1000

$1100

TFC

TC

TVC

TotalCost

VariableCost

FixedCost

8-16

Short-Run Production Costs

Cos

ts

1 2 3 4 5 6 7 8 9 100 Q

50

100

150

$200

AFC

MC

ATCAVC

AVC

AFC

8-17

Production Relationships• Marginal cost and diminishing returns• Marginal cost and marginal product• Marginal cost and average variable

cost• Marginal cost and average total cost• Production curves and cost curves• Shifts in cost curves

8-18

Aver

age

Prod

uct a

ndM

argi

nal P

rodu

ctC

ost (

Dol

lars

)

Graphical Relationships

MPAP

MCAVC

Quantity of Output

Quantity of Labor

Production Curves

Cost Curves

8-19

Long-Run Production Costs

• Choose your plant size• Minimize ATC• Different ATC curves

–Short run• Long run ATC

–Envelope of short run ATC

8-20

Long-Run ATC Curve

Aver

age

Tota

l Cos

ts ATC-1

ATC-2

ATC-3 ATC-4

ATC-5

Output

Any number of short-run optimum size cost curves can be constructed

8-21

Long-Run ATC Curve

Long-RunATC

Aver

age

Tota

l Cos

ts ATC-1

ATC-2

ATC-3 ATC-4

ATC-5

Output

The long-run ATC curve just“envelopes” the short run ATCs

8-22

Long Run Production Cost

• Economies of Scale–Labor specialization–Managerial specialization–Efficient capital

• Diseconomies of Scale• Constant Returns to Scale

8-23

Long-Run ATC Shapes

Output

Long-run ATC curve where economiesof scale exist

Aver

age

Tota

l Cos

ts

Long-RunATC

EconomiesOf Scale

Constant ReturnsTo Scale

DiseconomiesOf Scale

q1 q2

8-24

OutputLong-run ATC curve where costs arelowest only when large numbers areparticipating

Aver

age

Tota

l Cos

tsEconomies

Of ScaleDiseconomies

Of Scale

Long-RunATC

Long-Run ATC Shapes

8-25

OutputLong-run ATC curve where economiesof scale exist, are exhausted quickly,and turn back up substantially

Aver

age

Tota

l Cos

ts

Long-RunATC

EconomiesOf Scale

DiseconomiesOf Scale

Long-Run ATC Shapes

8-26

Key Terms• economic (opportunity)

cost• explicit costs• implicit costs• normal profit• economic profit• short run• long run• total product (TP)• marginal product (MP)• average product (AP)• law of diminishing returns• fixed costs

• variable costs• total cost• average fixed cost (AFC)• average variable cost

(AVC)• average total cost (ATC)• marginal cost (MC)• economies of scale• diseconomies of scale• constant returns to scale• minimum efficient scale

(MES)• natural monopoly

8-27

Next Chapter Preview…

PureCompetition

8-28