Psychometric

Psychometrics is the field of study concerned with the theory and technique of psychological measurement. It focuses on quantifying mental constructs such as intelligence, aptitude, personality, and other attributes through standardized tests and scales. The goal is to produce reliable and valid scores that inform decisions in education, employment, clinical work, and research.

Core concepts include reliability and validity. Reliability concerns consistency across time, items, and raters, while validity concerns accuracy in measuring the intended construct. Types of validity include content validity, criterion-related validity, and construct validity. Reliability is assessed using methods such as test-retest, inter-rater agreement, and internal consistency measures (Cronbach's alpha).

Standardization establishes uniform procedures for administration and scoring and provides normative data from representative samples to support interpretation.

Measurement models include Classical Test Theory and Item Response Theory. IRT links latent trait levels to item responses and allows item calibration. Common IRT models include one-parameter, two-parameter, and three-parameter models that address item difficulty, discrimination, and guessing.

Test development follows a sequence: define purpose and content domain, write items, pilot test, perform item analysis, evaluate reliability and validity, and create norms. Attention to fairness and cultural bias, along with ethical considerations such as informed use and reporting of limitations, is essential.

Applications span education (achievement and ability tests), psychology (personality inventories and clinical screening), and organizational settings (aptitude and personnel assessments). Limitations include measurement error, cultural bias, and ongoing challenges in establishing validity across diverse populations.