From service quality experience to advocacy in informal paratransit: A higher-order partial least squares structural equation modelling study in Vietnam

Background: In the context of the green transition and the sharing economy, informal paratransit such as shared rides, shared vans and shared minibuses is becoming an important part that is complementary to the formal public transport system in Vietnam. However, the majority of research in Southeast Asia only separately considers some of the service quality aspects and does not approach it from a general perspective about the service quality experience (SQE). Objectives: This study aims at testing the impact of SQE on satisfaction, loyalty intention and advocacy and word of mouth (WOM) of passengers within the context of informal paratransit in Vietnam. Concurrently, it clarifies the intermediate role of satisfaction in this relationship chain. Method: Service quality experience is conceptualised as a reflective–reflective higher-order construct, formed from five components, including the physical servicescape, in-vehicle amenities quality, staff assurance and empathy, price–value fairness and service system trust (SST). The survey data were collected from 333 passengers who used the informal paratransit service for the last 2 months and analysed by the two-stage approach partial least squares structural equation modelling (PLS-SEM). Results: The estimated results show that SQE positively and strongly affects satisfaction. Additionally, it directly influences and has statistical meaning for loyalty intention and positive WOM. Satisfaction holds a crucial intermediate role, converting the influence of SQE to both loyalty intention and positive WOM of passengers. Conclusion: SQE is the central foundation shaping customer behaviour within informal paratransit. The research extends the stimulus–organism–response (SOR) framework and expectation–confirmation theory (ECT) by modelling SQE as a higher-order construct linked with behavioural outcomes. Contribution: The findings suggest that transport providers and regulatory authorities need to invest in all five SQE components and integrate informal paratransit into Vietnam’s sustainable transport development system.