56 section 2 Supply and Demand
Factors That Shift DemandChanges in the prices of related goods or services
IfAandBaresubstitutes...... and the price of Brises,...... demand for Aincreases (shifts to
the right).... and the price of Bfalls,...... demand for Adecreases (shifts to
the left).
If A and Barecomplements...... and the price of Brises,...... demand for Adecreases.
... and the price of Bfalls,...... demand for Aincreases.
Changes in income
IfAis a normal good...... and income rises,...... demand for Aincreases.
... and income falls,...... demand for Adecreases.
IfAis an inferior good...... and income rises,...... demand for Adecreases.
... and income falls,...... demand for Aincreases.
Changes in tastes
If tastes change in favor of A,...... demand for Aincreases.
If tastes change against A,...... demand for Adecreases.
Changes in expectations
If the price of Ais expected to rise in the future,...... demand for Aincreases today.
If the price of Ais expected to fall in the future,...... demand for Adecreases today.
If A is a normal good...... and income is expected to rise in the future,...... demand for Amay increase today.
... and income is expected to fall in the future,...... demand for Amay decrease today.
If A is an inferior good...... and income is expected to rise in the future,...... demand for Amay decrease today.
... and income is expected to fall in the future,...... demand for Amay increase today.
Changes in the number of consumers
If the number of consumers of Arises,...... market demand for Aincreases.
If the number of consumers of Afalls,...... market demand for Adecreases.
table5.1
20 pounds of coffee beans per year and Dino demands 10 pounds per year. So the
quantity demanded by the market is 30 pounds per year.
Clearly, the quantity demanded by the market at any given price is larger
with Dino present than it would be if Darla were the only consumer. The quantity
demanded at any given price would be even larger if we added a third consumer,
then a fourth, and so on. So an increase in the number of consumers leads to an in-
crease in demand.
For an overview of the factors that shift demand, see Table 5.1.