[] () the way in which a change in the price of a product or service results in a change in the quantity demanded because the consumer is able to buy more or less with their money as a result of the price change收入效应（产品或服务的价格变化导致需求量的变化，原因是由于价格变化，消费者能够用自己的钱多买或少买）➡substitution effect