Lack of service due to incorrect staffing of the store to meet the number of customers is one of the main reasons of loss sales. A store who got a traffic of 3,000 visitors in a week, but sells only 15% to them, it’s just 450 transactions. This situation means that 2,550 people leaved the store without buying. If we want to enhance the sales of 5%, it’s necessary to sell to 23 of the 2,550 visitors who didn’t buy. Perhaps the mailman or delivery man comes a few times.