方法采用现况调查和危险因素病例对照研究法进行研究。
Methods Prevalence survey and case-control study on risk factors was conducted.
很多研究员都指责案例对照法不是展现因果关系直接有力的方法，尤其因为它受制于大量的记忆误差。
Many researchers fault case-control work as being a weak method for showing direct causality, especially because it is subject to substantial recall bias.
此外，设计者们还将每个研究对象的每种促销定价实验，与对照组实验进行对比，得出其额外的损失，然后再根据平均额外损失为五种促销定价方式排名，最终确定了最忽悠人/框人的促销方式为“复合定价法”，然后依次是“限时定价法”、“钓饵定价法”﹑“贱卖定价法”和“复杂定价法”。
The average extra loss was then used to rank the five price frames. Shoppers were worst off under drip pricing, followed by time-limited offers, baiting, sales and complex pricing.
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