An Author Co-Citation Analysis of Medical Informatics*
Andrews, James E., Journal of the Medical Library Association
Objective: This study presents the results of an author co-citation analysis of the interdisciplinary field of medical informatics.
Methods: An author co-citation analysis was conducted for the years 1994 to 1998, using the fifty most-cited American College of Medical Informatics fellows as an author population. Co-citation data were calculated for every author pair, and multivariate analyses were performed to ultimately show the relationships among all authors. A multidimensional map was created, wherein each author is represented as a point, and the proximity of these points reflects the relationships of authors as perceived by multiple citers.
Results and Conclusion: The results from this analysis provide one perspective of the field of medical informatics and are used to suggest future research directions to address issues related to better understanding of communication and social networks in the field to inform better provision of information services.
Medical informatics is an interdisciplinary field that draws from and contributes to a number of disciplines. It is a field that has a number of overlapping research foci within its boundaries and that often requires highly interactive collaboration among heterogeneous researchers. As a result, researchers and professionals in medical informatics may find it challenging to access and utilize the field's literature. Interdisciplinary fields such as medical informatics pose challenges to librarians and other information professionals who continually seek ways to reconcile relevant information sources with the needs of diverse user populations.
In support of this broad goal, library and information science (LIS) researchers and professionals have long benefited from understanding the scholarly communication structures and networks of the disciplines they serve. In LIS, the methodologies of bibliometrics have stood out as a compelling set of quantitative techniques used to understand the structure of disciplines. Bibliometrics seeks to quantitatively study the literatures of fields-primarily their bibliographies-to produce models of science, technology, and scholarship over time [I]. The intersection of bibliometrics and scholarly communication can be viewed as the application of the quantitative analyses of literature that enable qualitative assessments and interpretations of science and scholarly networks. The breadth of this intersection, of course, can be considered either narrowly or broadly. For instance, "some view the intersection narrowly, constituted only by the use of clustering methods to map relationships among disciplines or to identify scholarly communities" . In a broader sense, others consider "any bibliometric study necessarily to concern scholarly communication and almost any quantitative analysis of scholarly communication to be bibliometric" . Either of these might be oversimplifications, for it is the research questions, goals, and data that determine the information sought and the appropriate methods of interpretation.
This study uses the bibliometric method of author co-citation analysis (ACA), which has been a particularly compelling tool in LIS. ACA uses authors as the units of analysis and the co-citations of pairs of authors (the number of times they are cited together by a third party) as the variable that indicates their "distances" from each other. The underlying assumption of ACA is that the more two authors are cited together, the closer the relationship between them . Two- or three-dimensional maps are produced using multidimensional scaling tools available in such statistical software packages as SPSS or SAS. Each point on the map represents an author, and the proximity of these points reflects the relationships of authors as perceived by multiple citers . In effect, such maps can reveal clusters or networks of scientists in a given field. As White puts it: "This is a more rigorous grouping principle than that of typical subject indexing, because it depends not on perfunctory indication of content by nonspecialists, but on repeated statements of connectedness by citers with subject expertise" . …