Income Elasticity of Demand is a measure of responsiveness of demand to the changes in income and it involves demand curve shifts. It provides information on the direction of change of demand, given a change in income and the size of the change.
Formula for YED:
Percentage change in quantity demanded = %ΔQ
Percentage change in income %ΔY
Normal goods have a positive value of YED, while Inferior goods have a negative value of YED as shown in the graph below:
Normal goods: when income increases, demand for normal goods increases as well. An increase in income leads to an increase in consumption, demand shifts to the right
Inferior goods: when income increases, demand for this good falls. The demand curve shifts left as income rises. As income rises, the proportion spent on food tends to fall while the proportion spent on services tends to rise.
Necessity and Luxury goods
Necessity
YED 1 If a good has a YED that is greater than one, is has income elastic demand: a percentage increase in income produces a larger percentage increase in quantity demanded. Luxuries are income elastic goods. Like the I Phone or chewing gum.
Applications of Income and elasticity of demand
YED implication for producers and for the economy
Overt time the economy grows and the society’s income increases.
Increasing income means a rising demand for goods and services. If the average economic growth is 3% per year, goods and services have income elastic demand (YED >1) thus, the demand of these goods and services grows at a higher rate than 3%. Examples include Restaurants, Movies and Health care, (these goods and services are produced by industries that develop and expand more rapidly than the total income in the economy). Also the demands of other goods such as food, clothing and furniture which are inelastic have a rate of less than 3%, (these goods and services are produced by industries growing more slowly than