Regularity in individual shopping trips: Implications for duration models in marketing

Most models for purchase timing behavior of households do not take into account that many households have regular and non-shopping days. I propose a statistical model for purchase timing that exploits information on the shopping days of households. It delivers forecasts for the number of purchases in the next period and for the timing of the first and consecutive purchases. Purchase occasions are modeled in terms of a counting process, which counts the recurrent purchases for each household as they evolve over time. I illustrate the model for yogurt and detergent purchases and highlight its useful managerial implications.