The term assessment refers to a set of operations carried out in order to deliver a judgment or make a decision. A situation of assessment arises, for example, when candidates are evaluated in a personnel selection, students are examined to test their learning or patients are visited to make a diagnosis of them.

In companies and firms, for example, assessment center is a procedure that organizations can use in order to evaluate candidates, workers and employees. It makes use of different methods and techniques, some (i.e. interviews) descending from the so-called idiographic (or clinical) approach, and some (i.e. standardized instruments) descending from the so-called nomothetic (or psychometric) approach. When assessment center is carried out in order to train or develop people, it is called development center.

Assessment operations require a series of technical measures (for example in the conduction of interviews and observation, as well as in the administration of standardized instruments). They are so well-known and studied in literature that they make naive and improvised attempts to assessment no longer justifiable.