A study by Gedenk & Neslin (2010) revealed an inverted U-shaped relationship between purchase incidence and purchase requirements for multi-buys in price promotions. In other words, price promotions that require lower purchase quantities (e.g., buy 2 and get 20% off) tend to increase purchase incidence, while promotions that require higher quantities (e.g., buy 3, get 2 free) could lead to a decline in purchase incidence.