psychometrics

Psychometrics is the science of measuring mental capacities, traits, and processes. It focuses on the development, analysis, and interpretation of instruments such as tests, questionnaires, and rating scales that aim to quantify abilities, knowledge, attitudes, personality, and other psychological constructs.

The field has roots in 19th and early 20th-century work, with figures such as Francis Galton, Alfred Binet, and Charles Spearman contributing to ideas about measurement and intelligence. Its modern form integrates classical test theory, factor analysis, and, since the late 20th century, item response theory and other modern measurement models.

Key concepts in psychometrics include reliability, validity, standardization, and normative data. Reliability refers to the consistency of scores across occasions or items, while validity concerns whether a test measures the intended construct. Standardization ensures uniform administration and scoring, and norms provide reference points for interpreting individual scores.

Psychometric methods encompass test construction, item development and analysis, pilot testing, and statistical evaluation. Common analyses include reliability estimates (such as Cronbach’s alpha and test-retest reliability), exploratory and confirmatory factor analysis, and item response theory to model how item properties relate to latent traits. Fairness analyses, including differential item functioning, assess whether tests function similarly across groups.

Applications of psychometrics span education (achievement and aptitude testing), clinical assessment, personnel selection and organizational psychology, and research. The field also addresses ethical considerations, including bias, privacy, and responsible use of scores, with ongoing emphasis on validity, transparency, and continual refinement.

See also: standardization, measurement theory, educational psychology, personality assessment.