A ranking of universities should account for differences in their disciplinary specialization

A bibliometric analysis of the 50 most frequently publishing Spanish universities shows large differences in the publication activity and citation impact among research disciplines within an institution. Gini Index is a useful measure of an institution's disciplinary specialization and can roughly categorize universities in terms of general versus specialized. A study of the Spanish academic system reveals that assessment of a university's research performance must take into account the disciplinary breadth of its publication activity and citation impact. It proposes the use of graphs showing not only a university's article production and citation impact, but also its disciplinary specialization. Such graphs constitute both a warning and a remedy against one-dimensional approaches to the assessment of institutional research performance.