Applying a new Importance-Unsatisfaction-Improvement theory to prioritizing improvement alternatives for a sustainable port

Importance-Performance analysis, an advantageous method for analysis and decision-making, has been widely applied to many fields. The advantages and disadvantages of Importance-Performance analysis have been reported in previous literature. Previous studies proposed some revised or integrated methods for combining Importance-Performance analysis and other techniques to overcome the weaknesses of Importance-Performance analysis to increase measurement accuracy. However, the calculation procedures of those revised and integrated methods, including several methodologies, usually are complex. In addition, Importance-Performance analysis only focuses on customers' demands and neglects the practical viewpoints of the service providers' capabilities, e.g., finance, feasibility, land and resource availability, etc. Therefore, this study proposes a new Importance-Unsatisfaction-Improvement theory for analyzing and determining the priorities of improvement alternatives. This new Importance-Unsatisfaction-Improvement theory not only takes into account both the demands of customers and the supply capabilities of service providers but also has a simple calculation procedure. Finally, this study applied the new Importance-Unsatisfaction-Improvement theory to prioritize improvement alternatives for upgrading from a traditional port to a sustainable port in Taiwan. The results show that the priority alternatives comply with the practices of the port authority. As noted above, the new Importance-Unsatisfaction-Improvement theory is an easy-applicability research methodology that can efficiently explain complex customer behaviors, provide easy-to-implement improvement strategies and recommendations, and have calculation simplicity. It can be applied to solve decision-making problems in various fields in future studies.