A necessity is defined as a good having an income elasticity of demand between zero and 1. If income elasticity of demand of a commodity is less than 1, it is a necessity good. If the elasticity of demand is greater than 1, it is a luxury good or a superior good. A zero income elasticity of demand occurs when an increase in income is not associated with a change in the demand of a good.
221. A necessity is defined as a good having
A necessity is defined as a good having an income elasticity of demand between zero and 1. If income elasticity of demand of a commodity is less than 1, it is a necessity good. If the elasticity of demand is greater than 1, it is a luxury good or a superior good. A zero income elasticity of demand occurs when an increase in income is not associated with a change in the demand of a good.