A correlated random effects model for longitudinal data with non-ignorable drop-out : an application to university student performance

Published online: 28 December 2011Empirical study of university student performance is often complicated by missing data, due to student drop-out of the university. If drop-out is non-ignorable, i.e. it depends on either unobserved values or an underlying response process, it may be a pervasive problem. In this paper, we tackle the relation between the primary response (student performance) and the missing data mechanism (drop-out) with a suitable random effects model, jointly modeling the two processes. We then use data from the individual records of the faculty of Statistics at Sapienza University of Rome in order to perform the empirical analysis