The Role of Purchase Quantity in Assortment Choice: The Quantity-Matching Heuristic

Consumers often purchase multiple items from a product category on a single shopping trip. In doing so, they must frequently choose among items that are grouped in assortments, such as those offered by a particular store or brand. This article examines how the number of to-be-purchased items influences consumer choice among assortments. It is argued that when consumers are uncertain about their preferences, they are more likely to prefer an assortment for which the number of available options matches the desired purchase quantity. This prediction is based on the notion that a match between the size of an assortment and the number of to-be-purchased items enables consumers to simplify the selection process by eliminating the need to trade off the benefits and costs of individual choice alternatives—a strategy referred to as the “quantity-matching heuristic.” The theoretical predictions are supported by data from five empirical studies that offer converging evidence for the role of purchase-quantity goals in assortment choice and identify moderating factors and boundary conditions.