“…It has also been applied in a wide variety of fields of study, and particularly in those related labour, health, and education economics. Using this econometric technique it has, thus, been possible to study other topics, including how women combine work and family duties [38], the impact of migration on socio-economic status of the families [39], the relationship between mothers' work pathways and health [40], the impact of different degrees of activity on the psychological wellbeing of midlife and older adults [41], admission processes in the intensive care units of hospitals [42], the relationship between social class and obesity [43], the implications for the academic results of students of them combining work and study [44], the satisfaction and work-related decisions of people with doctorate degrees [45], and the impact of the choice of educational centre on the implication of parents in the education of their children [46]. However, to date, no applications of this econometric technique have been found in the field of transport, despite the fact that it makes it possible to approximate the effect of the unobserved characteristics of individuals on the outcome variable of the model.…”