Trends and challenges of implementing randomized controlled trials in English language education: a systematic review

Randomized Controlled Trials (RCTs) in English Language Education (ELE) have gained attention for assessing the efficacy of pedagogical interventions. Understanding RCT trends and challenges in their application in ELE is essential for improving educational practices. This systematic review aims to address this issue by investigating the trends and challenges of implementing RCTs in ELE. Following the PRISMA framework, we screened studies from Google Scholar, Semantic Scholar, ERIC, and OpenAlex against predefined inclusion criteria and appraised them using structured methodological standards for RCTs. Subsequently, we included 44 RCTs published in peer-reviewed journals over the last 15 years in ELE. Finally, we employed descriptive statistics to summarize the studies' characteristics and a narrative synthesis to identify patterns and gaps. Findings revealed a growing trend of RCTs in ELE, mostly led by Asian studies and technology-based interventions, with a focus on language skills at the university level. However, the reliance of most studies on small samples, simple randomization, short-term interventions, and the demand for rigid RCT procedures has revealed the methodological, ethical, contextual, and practical challenges of implementing RCTs in ELE. These findings offer valuable insights for researchers, EFL teacher-practitioners, policymakers, and curriculum designers to implement and practice robust RCTs in ELE.