Psychological tests are one of the sources of data used within the process of psychological assessment. Psychological testing provides ‘samples of behavior”, often responses to specific test questions or measures of observable behavior, in order to infer generalizations about a given individual. The technical term for the science behind psychological testing is psychometrics. A useful psychological test must be both reliable (i.e., produce internally consistent and stable results over time), and valid (i.e., there is evidence to support the specified interpretation of the test results). All research-based tests possess these qualities. Further, psychological measures that are grounded in research can be interpreted in a norm-referenced manner, allowing for an understanding of how an individual's scores compare with a referenced group (e.g., how one’s scores compare to others of the same age, gender, culture, or social class).