Necessary and sufficient conditions for attractive public Transport : Combined use of PLS-SEM and NCA

In order to effectively manage transportation systems, and improve the attractiveness of public transport, public authorities, policymakers and researchers need a better understanding of the conditions necessary for improving attractiveness and those that can be considered sufficient. The purpose of this study is to expand the analytical toolbox of transportation research and introduce an analytical approach to identifying and distinguishing between the conditions that are necessary and sufficient for a desired outcome. Specifically, we suggest a complementary approach to combining partial least square structural equation modelling (PLS-SEM) and necessary condition analysis (NCA) in order to examine which service quality attributes (functionality, information, security/safety, comfort, and cost) are sufficient, and what degree of satisfaction with these attributes is necessary for high overall travel satisfaction. The data consists of subjectively reported experiences from over 900 users of public transportation in four northern European countries. We find that, for high overall travel satisfaction, a minimum level of satisfaction with comfort (equal to 33.1%) is necessary. Furthermore, an increase in satisfaction with comfort, functionality/ reliability and cost is sufficient to improve overall travel satisfaction. This means that comfort is both a necessary and a sufficient condition, whereas functionality/reliability and cost are sufficient but non-necessary conditions in this context. We conclude that using this complementary approach can guide public transport managers and researchers in identifying important bottlenecks and establishing priorities for improving service quality, essential knowledge when developing effective strategies for attractive public transport services