ABSTRACT

The quantity purchased in a period is the result of two decisions: the frequency of purchase and the average purchase on each occasion. We introduce habit formation into demand systems modelling each of these decisions. An econometric model is estimated by Bayesian methods. The data generating processes of the frequency and quantity decisions are assumed to follow, respectively, a multivariate Poisson log-normal distribution and a multivariate gamma log-normal distribution. We estimate the systems using French scanner data for purchases of fish. The results suggest that habits in purchase frequencies are important, while habits in average purchased quantities are less important. Furthermore, we find that price changes are important for explaining average quantities purchased but have only minor effects on purchase frequencies.

摘要

一个时期内购买的数量是两个决定的结果：购买频率和每次购买的平均次数。我们将习惯的形成引入到对这些决策进行建模的需求系统中。计量经济模型是通过贝叶斯方法估计的。假设频率和数量决策的数据生成过程分别遵循多元泊松对数正态分布和多元伽马对数正态分布。我们估计系统使用法国扫描仪数据购买鱼。结果表明，购买频率的习惯很重要，而平均购买数量的习惯则不太重要。此外，我们发现价格变化对于解释平均购买数量很重要，但对购买频率的影响很小。