An Evaluation of Syntactic Complexity, Lexical Diversity and Text Length as Predictors of Foreign Language Writing Scores

The main premise of this study is to investigate to what extent syntactic complexity (SC), lexical diversity (LD), and text length (TL) correlate to foreign language (FL) writing quality scores assigned by human judges for the English essays of 204 pre-service teachers of English of two different curricular levels (first and fourth-year students). The study adopts a sequential-explanatory mixed-method research design. To that end, eight instructors rating student papers for 16 years on average were interviewed. The statistical analyses reveal that the 4th-year students outperformed the 1st-year students in TL, writing scores, and five indices of SC and LD. Subsequent regression analyses explained the variance in overall writing scores. The qualitative results showed variability in the instructors' ability to detect and prioritize these linguistic features, showing that while some instructors had a nuanced understanding of SC and LD, others emphasized overall content and organization more than linguistic complexity. The role of syntactic complexity, linguistic diversity, and text length as predictors of foreign language writing quality revealed that while human raters recognize these linguistic features to varying extents, their evaluation can be enhanced through standardized assessment practices and the integration of automated tools.