、需求收入弹性 (四)商品需求收入弹性理论的应用 a Income elasticity of demand is an important concept to firms considering the future size of the market for their product. If the product has a high income elasticity of demand. sales are likely to expand rapidly as national income rises but may also fall significantly if the economy moves into recession（四）商品需求收入弹性理论的应用 ▪ Income elasticity of demand is an important concept to firms considering the future size of the market for their product. If the product has a high income elasticity of demand, sales are likely to expand rapidly as national income rises, but may also fall significantly if the economy moves into recession. 一、需求收入弹性