A Hybrid Multi-Criteria Decision-Making Framework Based on Interval Type-2 Fuzzy Modelling for Sustainable Investment Project Selection

Selecting sustainable investment projects is a complex decision-making problem because economic, environmental, and social criteria must be considered simultaneously under uncertainty. This study develops a two-stage multi-criteria decision-making (MCDM) framework for sustainable investment project selection in the manufacturing sector, with uncertainty explicitly modelled using interval type-2 fuzzy sets. In the first stage, the Interval Type-2 Fuzzy Analytic Hierarchy Process (IT2FAHP) is applied to determine the weights of the sustainability dimensions based on the assessments of multiple decision-makers, while the criteria within each dimension are assumed to be equally important. In the second stage, investment projects are ranked using the Interval Type-2 Fuzzy Multi-Objective Optimization by Ratio Analysis (IT2FMOORA) and Interval Type-2 Fuzzy TODIM (IT2FTODIM) methods. Uncertain assessments are represented using interval type-2 triangular fuzzy numbers (IT2TFNs), and the proposed framework is tested through a real-world case study based on data and expert assessments obtained from a manufacturing company in central Serbia. The results show that both ranking methods identify the same project as the best alternative for forthcoming implementation. Overall, the proposed framework provides a structured decision-support approach for sustainable investment project selection by jointly considering economic, environmental, and social dimensions while explicitly addressing uncertainty in the decision-making process.