Contractors Selection Based on the Grey Decision Model

Contractor selection is a multiple-attribute decision-making (MADM) problem. Since the decision makers (DMs) such as preferences on alternatives or on the attributes of contractor are often uncertain, undefined, vague and fuzzy, contractor selection becomes more difficult. Current selection methods are reviewed and three main concepts are generated for selection: cost, time, and quality. The proposed selection model uses evaluation criteria related to these concepts. Grey theory is one of the methods used to study uncertainty, having advantage over other theory in the mathematical analysis of systems with uncertain and fuzz information. In this paper, we propose a new multi-criteria decision model for construction contractor selection based on the grey decision theory. This model can be used as a decision support system by project owners to identify an eligible contractor or tender to be awarded the contract. The work procedure is as follows: firstly, the weights and ratings of attributes for all alternatives are described by linguistic variables that can be expressed in grey numbers. Secondly, using a grey possibility degree, the ranking order of all alternatives is determined. Finally, an example of a selection problem of contractor is used to illustrate the proposed approach.