Know the difference!

Changes in demand/supply versus changes in “quantity demanded”/

“quantity supplied”

Changes in “quantity demanded”

Demand Schedule

Price of chocolate bars ($)

Quantity demanded of

chocolate bars

(per week)5 2

4 4

3 6

2 8

1 10

Chocolate bars

1

2

3

4

5

Pric

e

2 4 6 8 10Quantity

D (Demand)

A change in price always causes a

change in “quantity demanded.”

Changes in demandDemand Schedule

Initial price of chocolate bars

($)

Initial quantity demanded of

chocolate bars (per week)

Price of chocolate bars

after ∆ in income($)

Quantity demanded of

chocolate bars (per week) after ∆ in income($)

5 2 5 44 4 4 63 6 3 82 8 2 101 10 1 12

Changes in demand

Chocolate bars

1

2

3

4

5

Pric

e

2 4 6 8 10

D (Demand)

A change one of the non-price determinants

always causes a change in demand.

D1 (Demand)

Know the lingo!

When you write, “change in quantity demanded,”

make sure you are referring to the result of a price change. When you

write, “change (or shift) in demand,” make sure you are referring to the result of a change in a non-price

determinant!

Supply works the same way!

When you write, “change in quantity supplied,”

make sure you are referring to the result of a price change. When you

write, “change (or shift) in supply,” make sure you are referring to the result of a

change in a non-price determinant!

End.