Enoch O. Oladunmoye, PhD

Understanding Psychometric Measurement

Psychological research frequently involves constructs that cannot be observed directly. Intelligence, depression, anxiety, resilience, self-efficacy, psychological wellbeing, motivation, personality, social support and many other concepts are latent attributes inferred from observable responses or performances. Psychometric measurement provides the theoretical and statistical framework through which such constructs are operationalised, measured, evaluated and interpreted. Measurement, however, is not simply the assignment of numerical values to questionnaire responses. It involves a chain of theoretical and empirical decisions connecting a construct definition to observable indicators, scores, interpretations and intended uses. This Research Note examines the foundations of psychometric measurement by distinguishing constructs, variables, indicators, items, scores and measurement error. It explains the distinction between observed and latent variables, formative and reflective measurement perspectives, and the relationship between measurement models and substantive theory. Particular attention is given to the principle that a test score is not inherently valid or invalid: validity concerns the strength of evidence supporting interpretations and uses of scores for specified purposes and populations. The Note also introduces measurement error as a fundamental feature of psychological measurement, explains why reliability and validity must be evaluated as components of a broader measurement argument, and presents a practical twelve step workflow that researchers can follow, including how these concepts can be operationalised within PsychtrixWeb. Keywords: psychometrics, psychological measurement, latent variables, observed variables, constructs, measurement error, test scores, validity, reliability, PsychtrixWeb