Assessment is the process of measuring knowledge or skills. Assessment is often used in an educational context, but applies to many other areas as well.

There are two main types of assessment:

• Summative Assessment - Summative assessment is generally carried out at the end of a course or project. In an educational setting, summative assessments are typically used to assign students a course grade.
• Formative Assessment - Formative assessment is generally carried out throughout a course or project. Formative assessment is used to aid learning. In an educational setting, formative assesment might be a teacher (or peer) providing feedback on a student's work, and would not necessarily be used for grading purposes.

A common form of formative assessment is diagnostic assessment. Diagnostic assessment measures a student's current knowledge and skills for the purpose of identifying a suitable program of learning. Self-assessment is a form of diagnostic assessment which involves students assessing themselves.

Assessment (either summative or formative) can be objective or subjective. Objective assessment is a form of questioning which has a single correct answer. Subjective assessment is a form of questioning which may have more than one current answer (or more than one way of expressing the correct answer). There are various types of objective and subjective questions. Objective question types include true/false, multiple choice, multiple-response and matching questions. Subjective questions include extended-response questions and essays. Objective assessment is becoming more popular due to the increased use of online assessment (e-assessment) since this form of questioning is well-suited to computerisation.

Assessment should be valid and reliable. A valid assessment is one which measures what it is intended to measure. For example, it would not be valid to assess driving skills through a written test (alone); the most valid way of assessing driving skills would be through a combination of practical assessment and written test. Teachers frequently complain that some examinations do not properly assess the syllabus upon which the examination is based; they are, effectively, questioning the validity of the exam.

Reliability relates to the consistency of an assessment. A reliable assessment is one which consistently achieves the same results with the same or a similar cohort of students. Various factors affect reliability -- including ambiguous questions, too many options within a question paper, vague marking instructions and poorly trained markers.

A good assessment is valid and reliable. Note that an assessment may be valid but unreliable or reliable but invalid or unreliable and invalid. In practice, an assessment is rarely completely valid or entirely reliable.

Although validity and reliability are the main measures of an assessment, there are other considerations such as practicality (which relates to the feasibility of the assessment), fairness (which relates to its application across various cohorts - such as males and females) and authenticity (which relates to its realism).

Related topics

• Evaluation is the process of looking at what is being assessed to make sure the right areas are being considered.
• Measurement is the process of collecting information (for either an assessment or an evaluation).
• Educational Evaluation deals specifically with evaluation as it applies to an educational setting. No Child Left Behind (NCLB) is a government program that requires educational evaluation.