Someone who spends time devising tests to high technical standards and who make as considerable effort to understand a psychological variable e.g. ability, aptitude, skill, attitude, motivation, or personality trait. The 'metric' part refers to efforts to achieve an objective measure. Therefore, psychometricians are professional test designers. In order to design a test they will conduct research and follow vigorous steps in test development to produce a sound test. This will normally take many months as the test development entails stages of trialling with appropriate groups of people.

An expert in the field of psychometrics, or intelligence testing.

An individual who has training in the field of measurement and evaluation and who has experience in assessing people’s knowledge, skill, and ability. The psychometrician is experienced in applying methodologies that enhance the assessment instruments’ validity, reliability, and legal defensibility.