Joint purchasing decisions: a multivariate negative binomial approach

The analysis of household purchasing decisions for understanding consumption behaviour has received much attention recently, mainly because of the measurement error problems that appear when using expenditure data to approximate consumption. This paper discusses some empirical regularities of the household purchasing behaviour based on information about the number of purchases a household has declared having done during the survey period. The concern of this paper is two-fold. First, to show how to recover purchase frequency data from the Spanish Budget Survey (1990-1991). Second, to discuss some empirical regularities of the joint purchasing decisions based on multivariate negative binomial models.