Automated measurement of syntactic complexity in corpus-based L2 writing research and implications for writing assessment

Research investigating corpora of English learners' language raises new questions about how syntactic complexity is defined theoretically and operationally for second language (L2) writing assessment. I show that syntactic complexity is important in construct definitions and L2 writing rating scales as well as in L2 writing research. I describe the operationalizations of syntactic complexity measurement in corpus-based L2 writing research, focusing on the Biber Tagger (Biber, Johansson, Leech, Conrad, & Finegan, 1999), Coh-Metrix (McNamara, Graesser, McCarthy, & Cai, 2014), and L2 Syntactic Complexity Analyzer (Lu, 2010), which are three tools commonly used to automate syntactic complexity analysis. A review of findings from recent corpus-based L2 writing studies on the relationship of syntactic complexity to L2 writing quality follows. I conclude with a discussion of the implications of these multiple perspectives on the definition of syntactic complexity in L2 studies.