Mental accounting and small windfalls

de Katherine L. Milkman

We study the effect of small windfalls on consumer spending decisions by examining the purchasing behavior of a sample of online grocery shoppers over the course of a year. We compare the purchases customers make when redeeming a $10-off coupon they received from their online grocer with the purchases the same customers make when shopping without a coupon. The standard permanent income or lifecycle theory of consumption predicts that grocery spending will be unaffected by the use of a $10-off coupon, while a simple mental accounting framework predicts that such a coupon will increase spending on groceries. Controlling for customer fixed effects and other relevant variables, we find that grocery spending increases by $1.59 with the use of a $10-off coupon.