Presenting a method to evaluate the pre-qualification of urban contractors based on qualitative criteria using the multi-criteria decision-making technique of group TOPSIS

Choosing a contractor is always one of the important and fundamental issues in organizations that define activities for outsourcing. Municipalities often use a pre-qualification evaluation stage before the final selection of a contractor. In many cases, the pre-qualification evaluation of contractors is done only based on qualitative evaluation criteria, such as experience, knowledge in the field, good track record, financial and equipment capacity, technical capacity and planning. The high sensitivity of the employer in the fair selection of the contractor causes the opinions of a group of experts to be used instead of the opinions of an expert, however, the unethical behavior of an expert in supporting a contractor and giving him a high score down to others to choose that contractor. In this article, an innovative method is proposed to avoid such an event. In the proposed method of this article, based on the points given by the experts to the contractors, the weighting coefficient of each expert's point to each contractor is determined and the point given by each expert to each contractor is modified based on the weighting factor. Then the selection of the contractor has been done using the group TOPSIS technique and by weighting the criteria based on Shannon's entropy method. The innovative method has been tested in 30 problems and the final result of the proposed method has been validated by removing the wrong expert opinion.