Psychometrics is a field of study concerned with the theory and technique of psychological measurement. As defined by the US National Council on Measurement in Education (NCME), psychometrics refers to psychological measurement. Generally, it refers to the specialist fields within psychology and education devoted to testing, measurement, assessment, and related activities.
The field is concerned with the objective measurement of skills and knowledge, abilities, attitudes, personality traits, clinical constructs and mental disorders as well as educational achievement. Some psychometric researchers focus on the construction and validation of assessment instruments such as questionnaires, tests, raters’ judgments, psychological symptom scales, and personality tests. Others focus on research relating to measurement theory (e.g., item response theory; intraclass correlation).