The problems with the subject categories schema in the EigenFactor database from the perspective of ranking journals by their prestige and impact

Purpose – EigenFactor service went through some changes in 2011 before issuing the most current edition (EF‐2010) following the release of the 2010 edition of the Journal Citation Reports (JCR‐2010) in mid‐2011. Ranking journals by the EigenFactor Score (EFS) and the Article Influence Score (AIS) offered an additional pair of bibliometric indicators to assess the impact of journals in the (sub)disciplinary fields of the sciences and social sciences. In evaluating the clout, importance, and impact of journals it is essential to compare apples to apples, i.e. limiting the assessments to journals belonging to the same (sub)disciplinary areas. This paper aims to examine the quality of the subject categories created for EF‐2010 and of the JCR‐2010 subject categories as implemented within the EigenFactor services. Design/methodology/approach – The paper compares the adequacy of the subject categories in the JCR‐2010 and EF‐2010, examining the assignment of 77 information and library science journals and 50 business/marketing journals to the 64 subject categories used in EF‐2010. Findings – The study finds that EF‐2010 uses a very broad categorisation system of merely 64 subject categories along with the much more specific subject categories originally developed and enhanced for the JCR database of the Institute for Scientific Information (now Thomson‐Reuters). JCR‐2010 has four times as many categories than the former, and would offer a far more realistic comparison of the impact of comparable journals in EF‐2010 if the developers of the EigenFactor database had retained the assignment of the journals to the JCR subject categories. The inconsistency, inaccuracy and incompleteness of the journal classification practice in EF‐2010 creates a highly distorted picture of the standing of journals in their (sub)disciplinary leagues, and makes it very difficult for the users to reproduce the far more refined league lists of journals. Originality/value – The paper describes the most serious limitations and errors in the classification of journals in the EF‐2010 edition.