A type-2 fuzzy set model for contractor prequalification

- Prequalification is a multi-criteria decision making problem involving uncertainty.
- Interval type-2 fuzzy sets is used for a group version of the problem.
- It becomes feasible to compute with the 'footprint of uncertainty' (FOU).
- The FOU of each alternative can be compared in the final outcome.

Prequalification helps decision makers find the right contractor for the job, which is key to the successful delivery of a construction project. The procedure involves judging the suitability, capability and competency of the contractor on various criteria, using both anecdotal and empirical evidence. The evidence used is often imprecise and subjective, and so is the evaluation and decision making procedure. Type-1 fuzzy sets have been used in the prequalification procedure to handle uncertain information. However, type-1 fuzzy sets are unable to reflect the differences in opinion among experts involved in group decision making. The purpose of this paper is to propose a practical prequalification procedure that uses interval type-2 fuzzy sets to address both linguistic imprecision and differences of opinion. A numerical example shows how the proposed procedure is carried out and the benefits that result compared to a similar procedure using type-1 fuzzy sets.