AP_Krugman_Textbook

figure 5.3

A Movement Along the Demand

Curve Versus a Shift of the

Demand Curve

The rise in the quantity demanded when going

from pointAto pointBreflects a movement along

the demand curve: it is the result of a fall in the

price of the good. The rise in the quantity de-

manded when going from pointAto pointC

reflects a change in demand: this shift to the right

is the result of a rise in the quantity demanded at

any given price.

0 7 8.1 9.7 10 13 15 17

Quantity of coffee beans

(billions of pounds)

$2.00

1.75

1.50

1.25

1.00

0.75

0.50

Price of

coffee beans

(per pound)

D 1 D 2

AC

B

A shift of the

demand curve...

...isnotthe

same thing as

a movement along

the demand curve.

figure 6.3

Movement Along the

Supply Curve Versus

Shift of the Supply Curve

The increase in quantity supplied when

going from pointAto pointBreflects a

movement along the supply curve: it is

the result of a rise in the price of the

good. The increase in quantity supplied

when going from pointAto pointCre-

flects a change in supply: this shift to

the right is the result of an increase in

the quantity supplied at any given price.

0 7 10 11.2 12 15 17

Quantity of coffee beans

(billions of pounds)

$2.00

1.75

1.50

1.25

1.00

0.75

0.50

Price of

coffee beans

(per pound)

A movement

along the supply

curve...

S 1 S 2

A

C

B

...isnotthe

same thing as

a shift of the

supply curve.

Clearly labeled graphs help to explain complex ideas

Figure 5.3 shows the

difference between

movementalong the

demand curve and a

shiftin demand,

providing a clear

presentation of a

difficult topic.

Figure 6.3 in the following

module illustrates the same

concept for the supply curve

Color is used consistently

to distinguish between

demand (blue) and supply

(red) curves.

PREFACE xxix