Text Complexity of Cambridge-Delivered IELTS Academic Reading Tests: Comparability with IELTS Academic Reading Practice Tests from Other Publishers

Comparing language tests and test preparation materials holds important implications for the latter's validity and reliability. However, not enough studies compare such materials across a wide range of indices. Therefore, this study investigated the text complexity of IELTS academic reading tests (IRT) and IELTS reading practice tests (IRPrT). Fine-grained quantitative analyses were undertaken to delineate measures of lexical, syntactic, and discourse complexity across a corpus of 108 IRT and 108 IRPrT published by Pearson, Macmillan, and Cengage Learning. The results suggest little difference between IRT and IRPrT at the lexical level; however, there were significant differences in some measures of syntactic and discourse level complexity. The findings bear implications for stakeholders including learners as test takers, instructors, material developers, and language testing researchers. We interpret this to mean that while IRPrT materials are lexically conducive to the practice for IRT and can provide a similar experience, the IRPrT do show some differences in the amount of subordination and idea repetition at the discourse level. Therefore, instructors and learners may seek to supplement practice with these structures when preparing for IRT, and the designers of such practice materials should consider aligning these factors in the future.