Mapping oral collocational use by measuring collocational accuracy, complexity, and fluency across different proficiency levels

Abstract Speech production theories have underscored the significance of producing formulaic sequences, particularly collocations, in language. Yet, measuring collocational competence in second language (L2) speaking tests, especially in high-stakes assessments, is under-researched. Hence, this study aimed to measure Iranian test takers’ lexical and grammatical collocations in terms of three dimensions of accuracy, complexity, and fluency in the IELTS speaking test across various proficiency levels. To further explore the relationship between the dimensions of collocational competence, the study also investigated the association between IELTS test takers’ collocational complexity and their collocational accuracy and fluency. To achieve this, a corpus of 60 mock IELTS speaking tests with different proficiency levels (band scores of 6, 7, and 8) was collected, with 20 samples for each level, resulting in a total of 3,252 collocations. Results showed a positive correlation between collocation scores and higher band scores across accuracy, complexity (except for restrictedness), and fluency dimensions. Results from regression path analyses also showed no significant correlation between IELTS test takers’ collocational complexity and fluency, while a significant negative correlation was identified between their collocational complexity and accuracy. These findings highlight the significance of oral collocational competence as a key factor influencing overall oral proficiency, particularly in the context of preparation for high-stakes tests.