Reasons for validating evaluation instruments
Some psychometric researchers focus on the construction and validation of assessment instruments such as questionnaires, tests, raters' judgments, and personality tests.
Others focus on research relating to measurement theory (e.g., item response theory; intraclass correlation). Psychometricians usually possess a specific qualification, and most are psychologists with advanced graduate training.
Much of the early theoretical and applied work in psychometrics was undertaken in an attempt to measure intelligence.In addition to traditional academic institutions, many psychometricians work for the government or in human resources departments.Others specialize as learning and development professionals.For example, methods based on covariance matrices are typically employed on the premise that numbers, such as raw scores derived from assessments, are measurements.Such approaches implicitly entail Stevens's definition of measurement, which requires only that numbers are assigned according to some rule.
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Cattell also coined the term mental test, and is responsible for the research and knowledge which ultimately led to the development of modern tests.