ABSTRACT
Chapter 9 summarizes and discusses the key findings of the study concerning the main and interactions effects of test occasion, task type, and student initial proficiency level on six dimensions of students’ texts: grammatical, discourse, sociolinguistic, strategic, content, and source use. The findings suggested that the TOEFL-iBT® writing section can detect changes in some aspects of writing performance after instruction and that changes in test-takers’ essay characteristics are associated with changes in their overall English language proficiency and writing scores. Additionally, essays on the TOEFL-iBT® integrated and independent varied significantly in terms of various writing features, while initial proficiency was associated with significant variation in almost all aspects of writing examined in the study. However, changes in essay characteristics after instruction were often moderated by task type and student initial proficiency level. The study provides an initial description of the patterns of change in TOEFL-iBT® essay characteristics after L2 instruction and how these changes relate to test-taker initial L2 proficiency and task type. As such, the findings support several warrants underlying the explanation inference in the TOEFL-iBT® validity argument, including the test’s sensitivity to change in L2 writing performance. They also shed light on some of the linguistic features of L2 learners’ texts that change after L2 instruction; describe how differences in initial L2 ability relate to changes in the linguistic characteristics of L2 learners’ texts; and depict some of the linguistic features that distinguish writing performance at various levels of achievement in L2 learning. The chapter concludes with a discussion of several implications of the study for L2 writing assessment research and practice.
