Web impact factor: a bibliometric criterion applied to medical informatics societies' web sites.

Several methods are available to evaluate and compare medical journals. The most popular is the journal Impact Factor, derived from averaging counts of citations to articles. Ingwersen adapted this method to assess the attractiveness of Web sites, defining the external Web Impact Factor (WIF) to be the number of external pages containing a link to a given Web site. This paper applies the WIF to 43 medical informatics societies' Web sites using advanced search engine queries to obtain the necessary link counts. The WIF was compared to the number of publications available in the Medline bibliographic database in medical informatics in these 43 countries. Between these two metrics, the observed Pearson correlation was 0.952 (p < 0.01) and the Spearman rank correlation was 0.548 (p < 0.01) showing in both cases a positive and strong significant correlation. The WIF of medicalm informatics society's Web site is statistically related to national productivity and discrepancies can be used to indicate countries where there are either weak medical informatics associations, or ones that do not make optimal use of the Web.