The time that Italian students spend at university is remarkably longer than in other European universities. For this reason, the government has recently introduced new rules for academic courses, in order to reduce the issue of long term students. In addition to this, universities need to address the growing problem of students prematurely leaving university before completing their courses. This paper considers the analysis of the length of stay of groups of students at Milano-Bicocca University using Coxian phase-type distributions classified according to the student individual characteristics.