This article investigates the mechanisms that underlie the biases in price elasticities of demand in applying static demand models under dynamic demand, which have been pointed out by previous empirical studies. It studies three sources of biases: disregard of state variables (affecting short-run elasticity); inconsistent utility parameter estimates; and changing expectations of consumers (affecting long-run elasticity). Disregard of state variables, such as durable product holdings, which is not negligible but not paid much attention to in the literature, leads to an overestimate of short-run own elasticities. Inconsistent utility parameter estimates arises due to the failure to account for consumers’ future expectations and unobserved state variables. Changing expectations of consumers are not explicitly specified in the static model, and this also leads to biased results when applying static models. Regarding the magnitude of the biases, the first and the third sources of biases might induce large biases in price elasticities, especially when the focus is on the large conditional choice probability products. Possible remedies for the use of static demand models are also discussed.

本文探讨了在动态需求下应用静态需求模型时导致需求价格弹性偏差的机制，这在之前的实证研究中已经指出。它研究了偏差的三个来源： 忽视状态变量（影响短期弹性）；效用参数估计不一致；消费者的期望不断变化（影响长期弹性）。忽视状态变量，例如耐用品持有量，这一点不可忽视，但在文献中没有得到太多关注，导致对短期自身弹性的高估。由于未能考虑消费者的未来期望和未观察到的状态变量，导致效用参数估计不一致。静态模型中没有明确指定消费者不断变化的期望，这也导致应用静态模型时出现有偏差的结果。关于偏差的大小，第一和第三偏差来源可能会导致价格弹性产生较大偏差，特别是当重点是大条件选择概率产品时。还讨论了使用静态需求模型的可能补救措施。