Interdisciplinary scientific research (IDR) challenges the study of science from a number of fronts, including one of creating output science and engineering (S&E) indicators. This literature review began with a narrow focus on quantitative measures of the output of IDR, but expanded the scope as it became clear that differing definitions, assessment tools, evaluation processes, and measures all shed light on aspects of IDR. Key among the broader aspects are (a) characterizing the concept of knowledge integration, and (b) recognizing that it can occur within a single mind or as the result of team dynamics. Output measures alone cannot adequately capture this process. Among the quantitative measures considered, bibliometrics (co-authorships, collaborations, references, citations and co-citations) are the most developed, but leave considerable gaps in understanding. Emerging measures in diversity, entropy, and network dynamics are promising, but require sophisticated interpretations and thus would not serve well as S&E indicators. Combinations of quantitative and qualitative assessments coming from evaluation studies appear to reveal S&E processes but carry burdens of expense, intrusion, and lack of reproducibility. This review is a first step toward providing a more holistic view of measuring IDR; several avenues for future research highlight the need for metrics to reflect the actual practice of IDR
