在这篇论文(《Combining mixed logit models and random effects models to identify the determinants of willingness to pay for rural landscape improvements》)中提到Hanley的办法,固定效应模型如果要想包含不随时间变化的量可以和选择替代属性或者是选项的特定常数进行交互。Attributes of the individuals must, therefore, be interacted either with the choice-specific attributes or with the alternative specific constants (Hanley et al., 2001).