The purpose of this study is to examine the relationship between lexical richness and the grades on essays produced by Swedish university students of English in order to shed light on the extent to which lexical richness is a predictor of overall essay quality. To this end, essays produced by 37 advanced learners of English were analyzed using a lexical richness measure that calculates the proportion of advanced vocabulary. The lexical richness score of the student essays were related to the following three variables: essay grade, course grade and vocabulary knowledge as measured by three discrete-item tests.
In addition, a 14-item questionnaire administered to the teachers at the English department eliciting information about their essay assessment procedures was analyzed, in order to shed light on the relationship between the weight teachers put on lexical richness and the grade they award essays with different lexical richness profiles. The results show that there is a relationship between use of advanced vocabulary in student essays and the overall course grade. However, no relationship was found between lexical richness and overall essay quality as reflected by faculty teachers’ ratings. A possible explanation is that a majority of the surveyed faculty teachers state that their assessment of essay quality is primarily based on content and grammar features rather than lexical features.