I wear a number of hats within the broad filed of educational psychology. One is that of an applied psychometrician. Whenever anyone asks what I do, I receive strange looks when that title rolls out of my mouth. I then always need to provide a general explanation.
I've decided to take a little time and generate a brief explanation. I hope this helps.
The online American Psychological Association (APA) Dictionary of Psychology defines psychometrics as:
n. the branch of psychology concerned with the quantification and measurement of mental attributes, behavior, performance, and the like, as well as with the design, analysis, and improvement of the tests, questionnaires, and other instruments used in such measurement. Also called psychometric psychology; psychometry.
The definition can be understood from the two components of the word. Psycho refers to “psyche” or the human mind. Metrics refers to “measurement.” Thus, in simple terms, psychometrics means psychological measurement--it is the math and science behind psychological testing.
Applied psychometrics is concerned with the application of psychological theory, techniques, statistical methods, and psychological measurement to applied psychological test development, evaluation, and test interpretation. This compares to more pure or theoretical psychometrics which focuses on developing new measurement theories, methods, statistical procedures, etc. An applied psychometrician uses the various theories, tools and techniques developed by more theoretical psychometricians in the actual development, evaluation, and interpretation of psychological tests. By way of analogy, applied psychometrics is to theoretical psychometrics, as applied research is to pure research.
The principles of psychometric testing are very broad in their potential application., and have been applied to such areas as intelligence, personality, interest, attitudes, neuropsychological functioning, and diagnostic measures (Irwing & Hughes, 2018). As noted recently by Irwing and Hughes (2018), psychometrics is broad as “It applies to many more fields than psychology, indeed biomedical science, education, economics, communications theory, marketing, sociology, politics, business, and epidemiology amongst other disciplines, not only employ psychometric testing, but have also made important contributions to the subject” (p. 3).
Although there are many publications of relevance to the topic of test development and psychometrics, the most useful and important single source is “the Standards for Educational and Psychological Testing” (aka., the Joint Test Standards; American Educational Research Association [AERA], American Psychological Association [APA], National Council on Measurement in Education [NCME], 2014). The Joint Test Standards outline standards and guidelines for test developers, publishers, and users (psychologists) of tests.
Given that the principles and theories of psychometrics are generic (they cut across all subdisciplines of psychology that use psychological tests), and there is a standard professionally accepted set of standards (the Joint Test Standards), an expert in applied psychometrics has the skills and expertise to evaluate the fundamental, universal or core measurement integrity (i.e., quality of norms, reliability, validity, etc.) of various psychological tests and measures (e.g., surveys, IQ tests, neuropsychological tests, personality tests), although sub-disciplinary expertise and training would be required to engage in expert interpretation by sub-disciplines. For example, expertise in brain development, functioning and brain-behavior relations would be necessary to use neuropsychological tests to make clinical judgements regarding brain dysfunction, type of brain disorders, etc. However, the basic psychometric characteristics of most all psychological and educational tests (e.g., neuropsychological, IQ, achievement, personality, interest, etc.) assessment can be evaluated by professionals with expertise in applied psychometrics.
American Educational Research Association, American Psychological Association, & National Council on Measurement in Education (2014). Standards for Educational and Psychological Testing. Washington, DC: Author.
Irwing, P. & Hughes, D. J. (2018). Test development. In P. Irwing, T. Booth, & D. J. Hughes (Eds.), The Wiley Handbook of Psychometric Testing: A Multidisciplinary Reference on Survey, Scale and Test Development (pp. 3-49. Hoboken, NJ: John Wiley & Sons