The Role of Collocation and Vocabulary Size in the Writing Performance of Upper-intermediate Students in Iran

Vocabulary and collocation may contribute to effective communication. This study attempted to understand whether vocabulary size or collocation knowledge of upper-intermediate Iranian EFL learners better predicts their writing performance. For this purpose, three different tests including vocabulary size test (Nation and Beglar, 2007) collocation knowledge test (Nizonkiza, 2012), and a writing performance task were administered to sixty students. The results, analyzed through linear regression, showed that while both vocabulary size (β = .521, p= .00) and collocation knowledge (β = .268, p= .03) were important factors in EFL learners writing performance, vocabulary size was a better predictor of the students’ writing performance.