This reference price or ranges of price that form the reference price level are internal representations that may or may not correspond to any actual external price. The reference price concept is specific to an individual, a product category, a sales environment and a point in time. As such, an individual's reference price is unobservable and may not even be articulated by the individual. This reference price may be memory of the last price paid (accurate or not), last transaction price (Bruno, Che, & Dutta, 2012)