VandenBos, G. R. (Ed.) (2007). APA dictionary of psychology. Washington, DC: American Psychological Association.
- qualitative data: "data that are not expressed numerically, such as descriptions of behavior and experience. If desired, qualitative data can often be expressed quantitatively..."
- qualitative evaluation: "an evaluation method that yields narratives gathered primarily from unstructured methods of data collection, naturalistic observation, and existing records..."
- quantitative data: "data expressed numerically, such as test scores or measurements of length or width..."
- quantitative evaluation: "an evaluation method that yields numerical indices gathered primarily from formal (objective) methods of data collection, systematic and controlled observation, and a prescribed research design..."