Sales wave research: customers who are initially offered the product at no cost are re-offered it, or a competitor’s product, at slightly reduced prices. The offer may be made as many as 5 times. The number of customers continuing to select the product and their level of satisfaction is recorded
销售波段研究（销售波研究法）：最初免费提供产品的客户以略低的价格重新提供产品或竞争对手的产品。 报价可以多达5次。 记录继续选择产品的顾客数量及其满意度
