39
1 Chapter 1 Budget Constraint

Chapter 1

Embed Size (px)

DESCRIPTION

 

Citation preview

Page 1: Chapter 1

1

Chapter 1

Budget Constraint

Page 2: Chapter 1

2

CONSUMER THEORY

Consumer theory: consumers choose the best bundle of goods they can afford.

Page 3: Chapter 1

3

CONSUMER THEORY

Two parts to theory

1. “can afford”___ budget constraint

2. “best” ___ according to consumers’ preferences

Page 4: Chapter 1

4

Budget Constraints

consumption bundle :

(x1, x2, …,xn) __ how much of each good is consumed

Commodity prices are p1, p2, … , pn.

m __ money the consumer has to spend

Page 5: Chapter 1

5

Budget Constraints

A bundle (x1, … , xn) is affordable at prices p1, … , pn :

When p1x1 + … + pnxn mwhere m is the consumer’s (disposable) income.

Page 6: Chapter 1

6

Budget Constraints

The consumer’s budget set is the set of all affordable bundles

The bundles that are only just affordable form the consumer’s budget line.

Page 7: Chapter 1

7

Budget Set and Constraint for Two Commoditiesx2

x1

p1x1 + p2x2 = m is x2 = -(p1/p2)x1 + m/p2

so slope is -p1/p2.

m /p1

BudgetSet

m /p2

Page 8: Chapter 1

8

Budget Constraints For n = 2 and x1 on the horizontal

axis, the constraint’s slope is -p1/p2. What does it mean?

xpp

xmp2

1

21

2

Page 9: Chapter 1

9

Budget Sets & Constraints; Income and Price Changes

The budget line and budget set depend upon prices and income. What happens as prices or income change?

Page 10: Chapter 1

10

How do the budget set and budget constraint change as income m

increases?

Originalbudget set

x2

x1

Page 11: Chapter 1

11

Higher income gives more choice

Originalbudget set

New affordable consumptionchoices

x2

x1

Original andnew budgetconstraints areparallel (sameslope).

Page 12: Chapter 1

12

How do the budget set and budget constraint change as income m

decreases?

Originalbudget set

x2

x1

Page 13: Chapter 1

13

How do the budget set and budget constraint change as income m

decreases?x2

x1

New, smallerbudget set

Consumption bundlesthat are no longeraffordable.Old and new

constraintsare parallel.

Page 14: Chapter 1

14

Budget Constraints - Price Changes

What happens if just one price decreases?

Suppose p1 decreases.

Page 15: Chapter 1

15

How do the budget set and budget constraint change as p1 decreases

from p1’ to p1”?

Originalbudget set

x2

x1

m/p2

m/p1’ m/p1”

-p1’/p2

Page 16: Chapter 1

16

How do the budget set and budget constraint change as p1 decreases

from p1’ to p1”?

Originalbudget set

x2

x1

m/p2

m/p1’ m/p1”

New affordable choices

-p1’/p2

Page 17: Chapter 1

17

How do the budget set and budget constraint change as p1 decreases

from p1’ to p1”?

Originalbudget set

x2

x1

m/p2

m/p1’ m/p1”

New affordable choices

Budget constraint pivots; slope flattens from -p1’/p2 to -p1”/p2

-p1’/p2

-p1”/p2

Page 18: Chapter 1

18

Taxes, subsidies and rationing

1. Quantity tax ___ tax levied on units bought : p1 + t

2. Value tax ___ tax levied on rupees spent : p1 + αp1. Also known as ad valorem tax

3. Subsidies ___ opposite of a tax

a) p1 - s

b) p1 - µp1

Page 19: Chapter 1

19

Taxes, subsidies and rationing

4. lump sum tax or subsidy __ amount of tax or subsidy independent of the consumer’s choices. Also called a head tax or a poll tax.

5. Rationing ___ can’t consume more than a certain amount of some good

Page 20: Chapter 1

20

The Food Stamp Program

Food stamps are coupons that can be legally exchanged only for food.

How does a commodity-specific gift such as a food stamp alter a family’s budget constraint?

Page 21: Chapter 1

21

The Food Stamp Program

Suppose m = $100, pF = $1 and the price of “other goods” is pG = $1.

The budget constraint is then F + G =100.

Page 22: Chapter 1

22

The Food Stamp ProgramG

F100

100

F + G = 100; before stamps.

Page 23: Chapter 1

23

The Food Stamp ProgramG

F100

100

F + G = 100: before stamps.

Page 24: Chapter 1

24

The Food Stamp ProgramG

F100

100

F + G = 100: before stamps.

Budget set after 40 foodstamps issued.

14040

Page 25: Chapter 1

25

The Food Stamp ProgramG

F100

100

F + G = 100: before stamps.

Budget set after 40 foodstamps issued.

140

The family’s budgetset is enlarged.

40

Page 26: Chapter 1

26

The Food Stamp Program

What if food stamps can be traded on a black market for $0.50 each?

Page 27: Chapter 1

27

Shapes of Budget Constraints - Quantity Discounts

Suppose p2 is constant at $1 but that p1=$2 for 0 x1 20 and p1=$1 for x1>20.

Page 28: Chapter 1

28

Shapes of Budget Constraints with a Quantity Discount

m = $100

50

100

20 80

x2

x1

Budget Set

Budget Constraint

Page 29: Chapter 1

29

Shapes of Budget Constraints with a Quantity Penalty

x2

x1

Budget Set

Budget Constraint

Page 30: Chapter 1

30

Shapes of Budget Constraints - One Price Negative

Commodity 1 is stinky garbage. You are paid $2 per unit to accept it; i.e. p1 = - $2. p2 = $1. Income, other than from accepting commodity 1, is m = $10.

constraint ?

Page 31: Chapter 1

31

More General Choice Sets

Choices are usually constrained by more than a budget; e.g. time constraints and other resources constraints.

A bundle is available only if it meets every constraint.

Page 32: Chapter 1

32

More General Choice Sets

Food

Other Stuff

10

At least 10 units of foodmust be eaten to survive

Page 33: Chapter 1

33

More General Choice Sets

Food

Other Stuff

10

Budget Set

Choice is also budgetChoice is also budgetconstrained.constrained.

Page 34: Chapter 1

34

More General Choice Sets

Food

Other Stuff

10

Choice is further restricted by a time constraint.

Page 35: Chapter 1

35

More General Choice Sets

So what is the choice set?So what is the choice set?

Page 36: Chapter 1

36

More General Choice Sets

Food

Other Stuff

10

Page 37: Chapter 1

37

More General Choice Sets

Food

Other Stuff

10

Page 38: Chapter 1

38

More General Choice Sets

Food

Other Stuff

10

The choice set is theintersection of all ofthe constraint sets.

Page 39: Chapter 1

Thank YouFor Feed Back

[email protected]@internationaladvisers.net

39