Diagnostic assessment is a type of formative assessment particularly intended to diagnose areas of weakness, or misunderstanding, and strength.
The aim of diagnostic assessment is to reveal an underlying problem in learning or to find out about the learner's ways of learning, in order to help her/him achieve learning aims. This more detailed, in-depth type of formative assessment was called 'taking a closer look' in the original 5-14 assessment guidance. There are many forms of published 'diagnostic tests', but, in the ordinary course of teaching, the teacher's interaction and discussion with a pupil is often the most effective basis for this process.
A type of formative assessment that is used to identify specific learning difficulties and to indicate the nature of the difficulties. Source: Griffin, P. & Nix, P. (1991) Educational Assessment and Reporting: A New Approach, Harcourt Brace Jovanovich, Sydney: 264. See also ' formative assessment'.