Interval-Valued Spherical Fuzzy Extension of DEMATEL and Its Application in Early-Stage Investment

Decision-making trial and evaluation laboratory (DEMATEL) is a practical method used to analyze the interrelationships between criteria while evaluating their importance in multi-criteria decision-making (MCDM) problems. This paper proposes an extension to DEMATEL using a fuzzy set—specifically, an interval-valued spherical fuzzy set (IVSFS)—which is one of the latest fuzzy developments. In contrast to the fuzzy extensions of DEMATEL reported in the literature, this study proposes a new IVSFS version of the DEMATEL methodology that incorporates experts’ weights. The proposed IVSFS–DEMATEL methodology uniquely manages the weights of experts using the form of IVSFSs, differing from existing DEMATEL methodologies. Furthermore, it aims to maintain the fuzziness of operations until the later stages, unlike existing methodologies that implement defuzzification operations at the early stages. A real case study of an early-stage investment process is conducted to justify the feasibility and applicability of the proposed methodology. Sensitivity and comparison analysis are performed to confirm the validity of the results.