The Quantity Integration Effect: Integrating Purchase and Quantity Decisions Increases Sales

Customers often decide not only whether to purchase, but also what quantity to purchase, and marketers can implement selling formats that either separate or combine these two decisions. The current research compares the quantity-sequential (QS) selling format, under which shoppers first choose to purchase and then choose the quantity, with a quantity-integrated (QI) selling format, under which shoppers simultaneously indicate whether and how much to buy. Although many retailers use the QS format, the QI format yields higher purchase rates. Across various product offers with over 16,000 experimental observations, this simple change in framing increased the likelihood of purchase by 41% and increased the overall sales volume by 29%. While contextual factors (e.g., the verbiage used) may contribute to this effect, it is primarily driven by a heightened sense of psychological closure afforded by quantity integration. The authors discuss the practical and theoretical implications of these findings.