With the Shopper Engine, customer profiles can be created that allow conclusions to be made about sales-relevant customer characteristics and preferences. Customers can thereby be grouped and segment-specifically approached according to their purchasing behavior. This identifies articles that suit a customer, although he has not yet purchased them. The result is an individual buying recommendation for prospective purchases and customized promotions, which can be printed out in real-time as a voucher on the register receipt or be sent as a personalized advertisement.