The diagnostic assessment of writing is an important aspect of language
testing which has often been neclected in the literature. However, it is
an area which poses special challenges to practioners both in the
classroom and in large-scale testing situations. This book presents a
study which set out to develop and validate a rating scale specifically
designed for the diagnostic assessment of writing in an academic English
setting. The scale was developed by analysing a large number of writing
performances produced by both native speakers of English and learners of
English as an additional language. The rating scale was then validated
using both quantitative and qualitative methods. The study showed that a
detailed data-based rating scale is more valid and more useful for
diagnostic purposes than the more commonly used impressionistic rating
scale.