Gabriel Söderberg

Time series citation data: the Nobel Prize in economics

Citation time series are not easy to compile from the most popular databases. The Data for Research service of the JSTOR journal database is a large and high-quality sample of citations, weighted towards humanities and social sciences. It provides time series citation data over many decades, back to the origins of the constituent journals. The citation trajectories of Nobel Prize winners in economics are analyzed here from 1930 to 2005. They are described mathematically by means of the Bass model of the diffusion of innovations. A bell-shaped curve provides a good fit with most prize winner citation trajectories, and suggests that economic knowledge follows the typical innovation cycle of adoption, peak, and decline within scholarly careers and shortly afterwards. Several variant trajectories are described.

Hayek in Citations and the Nobel Memorial Prize

Citations are a currency of academic standing. Among scholars, priority of discovery is acknowledged in footnotes and references, and the number of citations is a measure of the impact of conceptual innovations. Citation counts were first assembled in the 1920s. The Science Citation index was launched in 1960, and a companion Social Science Citation index was added in 1975.1 Both are now part of the Thomson-Reuters ISI database, which is the most prominent citation database in use today. All citation counts have biases.2 ISI is proprietary and is not easy to work with; its coverage dwindles the further back you go, it has a restricted range of journals, only counts first authors, and only takes account of books if they appear in journal citations. Elsevier’s more recent Scopus database covers many more journals, but has a poor coverage of the distant past. An online source of citations, Google Scholar, is easy to use, and it counts books as well as publications in languages other than English. That is not a decisive argument against it, since most important journals are available online, but the findings are weighted towards the present and the scores are always in flux. It is also difficult to extract citation on a yearly basis.