“…The former refers to the knowledge of organizing utterances or sentences and texts such as lexical and grammatical knowledge, while the latter refers to the knowledge of using sentences and texts appropriately in situations (Bachman & Palmer, 1996, 2010. In previous studies, levels of L2 proficiency were determined by standardized test scores (e.g., Allami & Naeimi, 2011;Garcia, 2004;Nguyen, 2008;Taguchi, 2005Taguchi, , 2006Takahashi, 1996;Xu, Case, & Wang, 2009 ), course or grade levels (e.g., Bardovi-Harlig, 2008, 2011Félix-Brasdefer, 2007;Koike, 1996;Pinto, 2005), length of formal instruction (e.g., Bonganets, Kellerman, & Bentlage, 1987), and duration of residence in the target language community (e.g., Blum-Kulka & Olshtain, 1986;Decapua & Dunham, 2007). Among these proficiency determinants, standardized test scores and course or grade levels are considered to be more reliable indicators of proficiency because standardized test scores allow for comparison across test takers, and course/grade levels are usually determined by a systematic evaluation within a course or program, including placement tests, teacher assessment and oral interviews.…”