A QUANTITATIVE ASSESSMENT OF INTERDISCIPLINARY STRUCTURES IN SCIENCE AND TECHNOLOGY - CO-CLASSIFICATION ANALYSIS OF ENERGY RESEARCH

The wide diversity in subject matter and volume of research publications of large multidisciplinary areas often presents an insurmountable barrier in obtaining a comprehensive overview of its internal ("intellectual") structure. In this article it is shown that a systematic, quantitative examination of the contents of an area's research publications offers an empirical solution for this problem. This "co-classification analysis" is based on the network of interdisciplinary links between research fields contributing to such an area, as manifest in the co-occurrence of different subject-classification headings assigned to research publications. The analysis yields quantitative measures of: (1) the level of interdisciplinarity in contributing research fields; (2) the strength of interdisciplinary relations between these fields, as well as (3) graphical representations ("maps") of the interdisciplinary structure in single fields, as well as the area as a whole. Capabilities and limitations of this methodology, as an aid in research policy studies, are discussed by way of a Dutch science-policy-driven application to the area of energy research. Results are presented concerning the worldwide interdisciplinary structure of energy research, and the structure in Dutch publications on research sources of renewable energy. Findings of a subsequent validation study amongst Dutch scientists, R&D managers, and S&T policy makers support our assertion that the method is useful for certain analytical and descriptive purposes, but also point out limits in its range of application.