The cross elasticity of demand is a concept in economics where one measures the responsiveness of quantity demanded of one product when the price of another product is changed. Another name for this is the cross-price elasticity of demand. This is determined by calculating the change in the percentage of the quantity demanded of a product divided by the change in the price of another product. Since in a monopoly market, there is a total lack of close substitutes, the cross elasticity of demand is zero in its case.