Formative and reflective measurement models for analysing transit service quality

Transit service quality is a complex concept depending on different service aspects, such as service frequency and punctuality, comfort, cleanliness, information and so on. Transit service quality is generally measured through the satisfaction of the users with the service. There are relationships between the overall service quality and the different transit service aspects, and between each aspect and the characteristics describing it. Structural equation models represent a useful tool for exploring this kind of relationship and determining the influence of the different service characteristics on service quality. An investigated issue concerning structural equation models is the contrast between the formative and the reflective approach. The structural models proposed for measuring transit service quality have followed a reflective approach, according to which the latent variable (or the service aspect) is the cause of the observed measures (or the service factors describing the service aspect); but in this paper we investigate on the fact that formative variables could be considered to model the relationship among the service quality characteristics, supposing that the observed measures, which represent the service characteristics, form the latent construct. The findings from the comparison between the results obtained by applying the two different approaches suggest that the reflective model is surely more suitable for describing the phenomenon of passenger satisfaction with transit service quality. However, we retain that if some service aspects can be more conveniently investigated through a reflective approach, other service aspects could follow a formative approach in a better way.