This corpus of written first-, second-, and third-term assigments of students of English at Uppsala University, Sweden, was collected by Ylva Berglund and Margareta Westergren Axelsson 1999-2001. It is available (also) from Oxford Text Archive, http://www.ota.ahds.ac.uk/. The corpus was described with the IMDI metadata set for the ECHO project
It is organized in subcorpora according either to tasks (useful for comparing essays from different people facing the same task) or to individuals (that is, longitudinally; useful for comparing development over time in individual writers). Note that the two hierarchies are only two different ways of visualizing the corpus -- the data pointed to is identical for both .