Finally the Google PageRank algorithm, the core analysis tool of the current web is back to where its idea is originated from, scientific citation analysis. The recently launched SCImago Journal & Country Rank database uses an algorithm very similar to PageRank. It has a new metric: the SCImago Journal Rank (SJR). According to Nature:
A new Internet database lets users generate on-the-fly citation statistics of published research papers for free. The tool also calculates papers’ impact factors using a new algorithm similar to PageRank, the algorithm Google uses to rank web pages. The open-access database is collaborating with Elsevier, the giant Amsterdam-based science publisher, and its underlying data come from Scopus, a subscription abstracts database created by Elsevier.
The SJR also analyses the citation links between journals in a series of iterative cycles, in the same way as the Google PageRank algorithm. This means not all citations are considered equal; those coming from journals with higher SJRs are given more weight. The main difference between SJR and Google’s PageRank is that SJR uses a citation window of three years.
From now on every stat geek can compare journals to journals, countries to countries based on different metrics like citable documents, cites, self-cites or the new h-index and get a ticket to recursive heaven. Of course I started with the comparison of Nature and Science to find something very different. I couldn’t. I predict that self-cites will show a lot on how things are going on at different scientific journals and the stats will be used as serious arguments in many blog posts. But here let me share some graphs on the quick comparison of USA, UK and China in the category of Aging.
First graph: citable documents
Second graph: cites
How to explain the dramatic change? see comment 1 by Grady, the Gun.