How effective is task-based language teaching to enhance second language learning? A technical comment on Bryfonski and McKay (2019)

This commentary focuses on three methodological concerns regarding Bryfonski and McKay's (2019) meta-analysis of existing works on the effectiveness of task-based language teaching (TBLT). These are (1) loose inclusion criteria, (2) oversimplified outcome effect size calculation, and (3) neglect of influence of moderators. To rectify these issues, we conducted a new meta-analysis to build on the strengths of their work while correcting some flaws by aiming to afford more rigorous and valid insights for education practitioners, researchers, and decision makers. While Bryfonski and McKay (BM) reported a strong positive effect (d = 0.93), our results point to a more modest effect of TBLT on second language achievement (g = 0.61). Different from BM's claimed four moderators of the main effect (i.e. program region, institution type, needs analysis, and cycles of implementation), our meta-regression results indicate that only sample size and teacher-as-researcher suffice to account for the heterogeneity of the effect sizes. Given the reduced number of acceptable primary studies, our revised results should be interpreted with caution.