Item Response Theory (IRT) is proposed in literature for evaluating the customer satisfaction in private and public service. In this
work a particular version of IRT, known as Partial Credit Model (PCM), is proposed to analyse the satisfaction of university
students of a middle university of Southern Italy. Moreover, to consider the effects of different factors (degree course,
departments, presence of integrative teaching activities, etc) and their interactions, factorial differential item functioning
proposed for the Rasch model is extended to PCM.