Study quality in SLA

This study assesses research and reporting practices in quantitative second language (L2) research. A sample of 606 primary studies, published from 1990 to 2010 in Language Learning and Studies in Second Language Acquisition, was collected and coded for designs, statistical analyses, reporting practices, and outcomes (i.e., effect sizes). The results point to several systematic strengths as well as many flaws, such as a lack of control in experimental designs, incomplete and inconsistent reporting practices, and low statistical power. I discuss these trends, strengths, and weaknesses in comparison with methodological reviews of L2 research (e.g., Plonsky & Gass, 2011) as well as reviews from other fields (e.g., education, Skidmore & Thompson, 2010). On the basis of the findings, I also make a number of suggestions for methodological reforms in applied linguistics.