To Buy or How Much to Buy? Partition Dependence in Purchase-Quantity Decisions

Tavassoli, N T and Visentin, M (2022) To Buy or How Much to Buy? Partition Dependence in Purchase-Quantity Decisions. Marketing Letters, 33 (2). pp. 177-188. ISSN 0923-0645

Abstract

Four studies demonstrate that people are more likely to buy (but not to buy more) when directly asked how much to buy in response to a set of purchase quantities (0, 1, 2 … n) than when first asked whether to buy in response to a seemingly innocuous yes/no purchase-interest question. This finding is explained in terms of response-scale partitioning. A purchase-quantity scale has a single negative (0) and multiple (n) positive response options. In contrast, a dichotomous yes/no purchase-interest question has an equal proportion of negative (“no”) and positive (“yes”) response options, the latter of which subsumes all positive quantity options into one partition. Ascertaining purchase interest using a single negative and multiple positive response options (“No”, “Mildly”, “Somewhat”, “Likely”, “Very”, and “Definitely”) eliminated the effect.