Focused information retrieval & english language instruction: A new text complexity algorithm for automatic text classification

Abstract

The purpose of the present study was to delineate a range of linguistic features that characterize the English reading texts used at the B2 (Independent User) and C1 (Advanced User) level of the Greek State Certificate of English Language Proficiency (KPG) exams in order to better define text complexity per level of competence. The main outcome of the research was the L.A.S.T. Text Difficulty Index that makes possible the automatic classification of B2 and C1 English reading texts based on four in-depth linguistic features, i.e. lexical density, syntactic structure similarity, tokens per word family and academic vocabulary. Given that the predictive accuracy of the formula has reached 80% on a new set of reading comprehension texts with 32 out of the 40 new texts assigned to similar levels by both raters, the practical usefulness of the index might extend to EFL testers and materials writers, who are in constant need of calibrated texts.