In economics, the income elasticity of demand (YED) is the responsivenesses of the quantity demanded for a good to a change in consumer income. It is measured as the ratio of the percentage change in quantity demanded to the percentage change in income. For example, if in response to a 10% increase in income, quantity demanded for a good or service were to increase by 20%, the income elasticity of demand would be 20%/10% = 2.0.