A conceptual evaluation of measures of interdisciplinarity

While interdisciplinary research has attracted much attention, this has not yet resulted in a coherent body of knowledge of interdisciplinarity. One of the impediments is a lack of consensus on its conceptualization and measurement. Some of the proposed measures have shown to misalign empirically, meaning that conclusions about IDR can differ across measures. To clarify this disagreement conceptually, and to stimulate better coherence in measurement, this paper starts with a review of the IDR definitions. From a synthesis of these definitions, we provide a conceptual definition of the construct along with evaluation criteria for its measures. We use these to evaluate current measures of IDR. The results show that most measures meet the usability criteria, but measures vary widely in meeting other criteria, which can explain some of the observed inconsistencies in earlier studies. The "Integration score" from Rafols and Meyer performed best. By using the results in selecting measures, researchers can, in our view, draw more consistent conclusions, aiding in the development of a coherent body of knowledge of this ever-important phenomenon.