Purposes of Assessment

Educational assessment is conducted for a variety of reasons and the nature of the assessment often reflects the purpose for which it is being carried out. The importance of validity and reliability differs somewhat depending on the purpose of assessment. Education professionals use a range of terms to refer to the different purposes of assessment. Those most commonly used include the following:

Diagnostic assessment

Diagnostic assessment may also be called 'pre-teaching' assessment or 'pre-learning' assessment. It is conducted before a particular programme or course of teaching starts in order to ascertain the knowledge, skills, strengths and weaknesses that the students already have. This diagnosis should enable the teacher to tailor their forthcoming teaching to the target group, or possibly even to each individual in the group. Diagnostic assessment may also be used to group or set students according to their current proficiency in the subject concerned. Validity and reliability are therefore important features of diagnostic assessment.

Formative assessment

Formative assessment may also be referred to as 'assessment for learning' or 'assessment for teaching'. It is carried out at regular intervals in the course of teaching and is intended to support and improve teaching and learning. It can be seen as an ongoing diagnostic tool that enables the teacher to adjust their teaching plans in the light of what students have (and have not) learned so far. Formative assessment is likely to be informal and low-key to the extent that students may hardly realise that they are being assessed. The assessment may be carried out on groups of students, with the teacher observing what they are able to do. Consequently the outcomes of formative assessment may be generalised rather than specific, helping the teacher to decide what still needs to be taught. Formative assessment is likely to place greater emphasis on validity than reliability, since the outcomes are generally 'low-stakes' and not intended to grade or rank those being assessed.

Summative assessment

Summative assessment is also known as 'assessment of learning' or 'assessment of attainment'. It takes place at the end of a course of teaching in order to ascertain what has been learned by the students. Summative assessment is usually formal and rigorous and likely to be conducted under controlled conditions. The outcome of summative assessment usually takes the form of a mark or grade which may be used to put candidates into a rank order and/or for the purposes of selection for a further stage. Summative assessment is usually therefore seen as a 'high-stakes' activity. Validity and reliability are consequently both of high importance in summative assessment.

Views differ regarding the effects of summative assessment on teachers and learners. Some argue that emphasis on summative assessment leads to 'teaching to the test' and consequent narrowing of the curriculum. Others maintain that summative assessment helps to raise achievement by giving teachers and learners clear objectives to aim for.

Evaluative assessment

Evaluative assessment is used to ascertain the success of a particular school or teacher, so the focus is not on the individual student or learner but on the overall outcomes for a group of students. In other words it is used for quality assurance purposes. Key stage tests, for example, are used to measure the effectiveness of teaching and learning in schools as much as to assess how well individual children are performing in the subjects concerned.