Psychometrics is a science that deals with the techniques of measuring psychological phenomena such as knowledge, skills, attitudes, characteristics and personal characteristics. The subject of research is usually the differences between individuals or between groups of individuals. Psychology is used as auxiliary science within psychology, sociology, economics, marketing and other social sciences.
Within psychometrics, the main areas of research are the formulation and refinement of the theoretical underpinnings of measurement in itself, as well as the development and refinement of specific psychometric measuring instruments such as the questionnaire (see psychometric instrument). Examples of psychometric instruments are the intelligence quotient and standardized reading and calculation skills tests.
In terms of methods and techniques, psychometrics makes extensive use of classical test theory and item-response theory as well as statistical techniques such as principal component analysis and factor analysis.