Balancing the additional costs of purchasing and the vendor set dimension to reduce public procurement costs

The paper addresses the reduction of the total cost of purchasing in public procurement, focusing on tenders called for in the European Union and awarded by the Lowest Price (LP) criterion. Taking into account the main characteristic features of governmental purchasing (competition, prescribed procedures, and transparency) and building upon the related contributions in the literature, we present a probabilistic approach for evaluating and limiting the total cost of purchasing in public tenders awarded according to the LP criterion. The presented framework includes the evaluation of the so-called additional costs of purchasing (ACP), a part of the transaction cost that is typically considered in the related literature from a private organization perspective only. The approach can be applied to a generic transaction in any public tender issued according to the European legislation with the LP criterion. Considering the real case study of the public tender for maintenance works on a municipal sport facility in Bari (Italy), we take into account the costs of both transaction counterparts, i.e., the ACP regarding the contracting authority and those related to the firms involved in the tender. Applying the model to the case study, we underline the relevance of ACP for public tenders and show that, by inviting a suitable number of bidders to participate in the call, it is possible to save money both for the contracting authority and the involved competitors.