A new multi-period optimization model for resilient-sustainable project portfolio evaluation under interval-valued Pythagorean fuzzy sets with a case study

In project portfolio selection, a set of goals is considered that is derived from the strategies and missions of firms. Due to the importance of social and environmental aspects of decision making in recent years, several attempts have been made to address sustainability in project portfolio selection. Given the turbulent environment and market conditions, one of the issues that has been the focus point of many scholars and practitioners is resilience. Simultaneous consideration of resiliency and sustainability in business environments is a new trend that has recently emerged. In this paper, to improve the decision-making process of firms in project portfolio selection, a novel resilient-sustainable project portfolio evaluation and optimization process is introduced. This new approach is based on two main phases. First, the projects are separately evaluated based on resiliency and sustainability criteria. In this process, weights of decision-makers and criteria are computed by new processes, and also the concept of linear assignment is applied. Then, in the second phase, a new multi-objective mathematical model is presented that aims at presenting a portfolio of multi-period projects with objectives of sustainability, resilience, and skill utilization. Then, the concept of the VIKOR method is applied to make an equivalent model and find the best portfolio. To address uncertainty in this process, interval-valued Pythagorean fuzzy sets (IVPFSs) are used. Utilization of such sets provides the process with high power in expressing the agreements, disagreements, and hesitations of project experts. To display the application steps of this method, a case study in petrochemical projects is presented and solved. The results show that the method can assist project portfolio managers in selecting and planning projects in addition to selecting the best project manager for each period of each project. Moreover, the manager can consider sustainability and resiliency in the selection and implementation of the projects.