title: PageRank as a method to rank biomedical literature by importance.
abstract: BACKGROUND
  Optimal ranking of literature importance is vital in overcoming article overload. Existing ranking methods are typically based on raw citation counts, giving a sum of 'inbound' links with no consideration of citation importance. PageRank, an algorithm originally developed for ranking webpages at the search engine, Google, could potentially be adapted to bibliometrics to quantify the relative importance weightings of a citation network. This article seeks to validate such an approach on the freely available, PubMed Central open access subset (PMC-OAS) of biomedical literature.
  
  
  RESULTS
  On-demand cloud computing infrastructure was used to extract a citation network from over 600,000 full-text PMC-OAS articles. PageRanks and citation counts were calculated for each node in this network. PageRank is highly correlated with citation count (R = 0.905, P < 0.01) and we thus validate the former as a surrogate of literature importance. Furthermore, the algorithm can be run in trivial time on cheap, commodity cluster hardware, lowering the barrier of entry for resource-limited open access organisations.
  
  
  CONCLUSIONS
  PageRank can be trivially computed on commodity cluster hardware and is linearly correlated with citation count. Given its putative benefits in quantifying relative importance, we suggest it may enrich the citation network, thereby overcoming the existing inadequacy of citation counts alone. We thus suggest PageRank as a feasible supplement to, or replacement of, existing bibliometric ranking methods.
authors.affiliation: College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT UK.
authors.forename: Elliot J
authors.initials: EJ
authors.lastname: Yates
authors.affiliation: College of Medical and Dental Sciences, University of Birmingham, Birmingham, B15 2TT UK.
authors.forename: Louise C
authors.initials: LC
authors.lastname: Dixon
keywords: Bibliometrics; Citation count; Impact factor; Journal ranking; PageRank