Noun phrase complexity, Academic level, and First- and Second-English Language Background in Academic Writing LanGe 2020 <div>Since the 1990s, grammatical complexity is a topic that has received considerable attention in various fields of applied linguistics, such as English for academic purposes, second language acquisition, language testing, and second language writing (Bulté & Housen, 2012). Many scholars in applied linguistics have recently argued that grammatical complexity has primarily been represented by clausal features (e.g., subordinate clauses), and it is important to study grammatical complexity as a multidimensional construct based on both clausal features and phrasal features (Biber, Gray & Poonpon, 2011; Norris & Ortega, 2009). Thus, this dissertation is a corpus-based investigation on how the use of noun phrases is influenced by two situational characteristics of a university context: academic level and first- and second-English language background.</div><div><br></div><div>I built my corpus by extracting 200 essays from British Academic Written English Corpus, which represents academic writing of (1) undergraduate and graduate students and (2) L1 and L2 students. Noun phrase complexity was then operationalized to the 11 noun modifiers proposed in the hypothesized developmental index of writing complexity features in Biber, Gray and Poonpon (2011). The 11 noun modifiers were extracted from the corpus and counted for statistical analysis via a set of Python programs. With a Chi-square test followed by a residual analysis, I found that both academic level and first- and second-English language background influenced noun phrase complexity but in distinct ways. The influence of academic level is primarily associated with three phrasal modifiers (i.e., attributive adjectives, premodifying nouns, and appositive NPs) and two clausal modifiers (i.e., relative clauses and noun complement clauses). The undergraduate corpus includes more of the two clausal modifiers, whereas the graduate corpus has more of the three phrasal modifiers. This suggests that, in these 200 essays, graduate students tend to build more compressed NPs than undergraduate students. However, the influence of first- and second-English language background derives from a much broader range of noun modifiers, including eight noun modifiers (e.g., attributive adjectives, relative clauses, infinitive clauses). More diverse NP patterns with different noun modifiers are in the L1 corpus than in the L2 corpus. Surprisingly, the L2 corpus has more phrasal noun modifiers (i.e., attributive adjectives, premodifying nouns), which has been argued to indicate advanced levels of academic writing. A qualitative analysis on selected essays reveals that some cases of attributive adjectives and premodifying nouns are repeatedly used by L2 students to help content development in their writing. Overall, this dissertation adds an additional piece of evidence on the importance of noun phrase complexity in writing research.</div><div><br></div>