The predictive validity of IELTS scores: a meta-analysis

Thousands of education institutions worldwide rely on IELTS scores as criteria for accepting international students whose first language is not English. Individual studies have found varying degrees of strength of correlations and conflicting results between IELTS entry scores and subsequent academic success. These conflicting results were examined through a meta-analysis, while also investigating multiple moderating variables: research funding bias, individual skill scores, level of study, country of study, and presence of additional English courses. Results from 20 studies show an approaching-small effect size of r = .231 for the relationship between IELTS scores and post-secondary GPA. The majority of macro skills (listening, writing, and speaking) do not reach the small effect size, however reading approaches it with an effect size of r = .232. Most moderator analyses were inconclusive owing to the small number of studies, but potential differences from individual studies are examined and discussed.