The sales force sizing problem with multi-period workload assignments, and service time windows

Abstract

This work introduces the sales force sizing problem with multi-period workload assignments, and service time windows. The motivation of the problem arises from a real life situation faced by a goods distribution company. The problem consists in determining the size of the sales force (i.e. the number of vendors to hire) and their daily schedules, within a planning horizon, to serve a set of customers in order to minimize the total nominal wage. There are different categories of customers and each customer has multiple time windows depending on the service day. Furthermore, the nominal wage of a hired vendor is determined by the most expensive category of the customers he serves. A mixed integer linear formulation and a heuristic are proposed for this problem. The performance of the heuristic algorithm is assessed over a set of instances adapted from literature. Computational results reveal the efficiency and scalability of the proposed procedure, providing a better tradeoff in terms of solution quality and running time than a commercial solver.