1. By Alexander Bowling Graphing Supply and Demand Shifters

2. Changes in Demand “IRDL” – Increase Right, Decrease Left
Changes in any of the factors other than price causes the demand curve to shift either:
Decrease in Demand shifts to the Left (Less demanded at each price) OR
Increase in Demand shifts to the Right (More demanded at each price)
“IRDL” – Increase Right, Decrease Left

3. Remember “IRDL” – Increase Right, Decrease Left
IRDL rhymes with turtle
Here’s IRDL the turtle

4. Changes in Demand
Several factors will change the demand for the good (shift the entire demand curve)
As an example, suppose consumer income increases. The demand for Widgets at all prices will increase.

5. Changes in Demand
Demand will also decrease due to changes in factors other than price.
As an example, suppose Widgets become less popular to own.

6. Demand Practice Graphing the Shifts

7. Demand decreases. The curve moves to the left.
1. The income of the Pago-Pagans declines after a typhoon hits the island.
Demand decreases. The curve moves to the left.
Price D D1
Quantity

8. Demand increases. Curve shifts to the right.
2. Pago-Pago is named one of the most beautiful islands in the world and tourism to the island doubles.
Demand increases. Curve shifts to the right.
Price D1 D
Quantity

9. 3. The price of Apple computers decreases
3. The price of Apple computers decreases. The demand for Dell computers decreases (substitute good).
Price
“IRDL” D D1
Quantity

10. Toothbrushes and toothpaste are complements
4. When the price of toothbrushes decreases, the demand for toothpaste increases.
Price
“IRDL”
Toothbrushes and toothpaste are complements D1 D
Quantity

11. 5. The Pillow Pet Manufactures decide to add a money back guarantee on their product, which increases the popularity for them.
Price D1 D
Quantity

12. 6. Many Pago-Pagans begin to believe that they may lose their jobs in the near future. (Think expectations!)
Price D D1
Quantity

13. 7. Come up with your own story. Grab a 3 x 5 card
7. Come up with your own story. Grab a 3 x 5 card. Write down the story on the front. On the back, draw the change in demand based on the story, and explain why demand changed. (Refer to your shifters notes). Give the card to your teacher.
Price D
Quantity