Measuring researcher independence using bibliometric data: A proposal for a new performance indicator

Bibliometric indicators are increasingly used at the individual level – as is exemplified by the popularity of the H-index and many other publication and citation based indicators used in evaluation. The issue isn’t whether these indicators can be considered useful, as they do provide a description of a researcher’s oeuvre. However, at the same time, they are not enough to assess the quality of a researcher and his/her oeuvre: Quality has more dimensions than productivity and impact alone. In this paper, we argue that independence is an equally important characteristic that however lacks validated indicators for measuring it at the individual level. We propose two indicators to measure different dimensions of independence: one assessing whether a researcher has developed an own collaboration network, and another assessing the level of thematic independence. We illustrate how these indicators distinguish between researchers that are equally productive and have similar impact. The independence indicator is a step forward in evaluating individual scholarly quality: in cases where citations and publications do not distinguish, the indicators for independence may do.