This paper reports on an investigation into the response validity of the IELTS Writing Subtest. The general purpose of the study was to identify factors in the assessment context which may influence candidates' achievement on the writing test.
The first part of the study examines the readability of test prompts and identifies discourse and pragmatic features which may influence candidates' comprehension of the prompts.
The second part of the study describes and analyses the test taking behaviours of intending IELTS candidates on the IELTS Writing Subtest. The analysis in this section is based on researchers' observations of subjects, on verbal protocols recorded as subjects wrote their responses, and on post-test interview data recorded with the same subjects.
The analysis for readability suggests that candidates' understanding of the test prompts is influenced by factors such as the purpose described for the tasks and the lexico-grammar of the tasks. The analysis of the test-taking behaviours of subjects points to socio-cultural influences on candidates' demonstration of their writing ability.
The study suggests the usefulness of using qualitative procedures such as verbal protocols for the investigation of response validity.