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.