Methodological approach for the study of elliptical constructions in student writing . In the frame of the écri + research project that aims to increase written skills in French at the university, this research presents a study about elliptical constructions which are among the most revealing difficulties of the level of writing. A corpus of erroneous constructions has been built from student writings. Different methodological choices have been made in order to identify the most frequent faulty ellipsis and the most recurring type of errors. We present a quantitative analysis of these errors according to the type and nature of the writings and their typology.