Google Scholar and Google WebURL Citation some evidence

Google Scholar and Google Web/URL Citation: some evidence of scholarly patterns on the Web Aims l l Correlation between ISI citation counts and either Google Scholar or Google Web/URL citation counts for articles in OA journals in eight disciplines Overlap between ISI and Google Scholar citations Characteristics of non-overlapping Google Citations with ISI Classification of web sources targeting articles

Data collection Well known and used formal scholarly citations. High impact journals Also formal web-extracted citations. But not much information about its quality Formal, informal and navigational “citations”.

Results 1 - Conventional citations correlate with Web-extracted citations (quantitative evidence) l ISI citations correlate with Google Scholar citation (journal/article level) l l ISI citations correlate with Google Web/URL citations (but weaker than above) l l Google Scholar citations were more numerous than ISI citations in computer science and the four social science disciplines “Article title” OR URL -site: journal URL address Higher correlations between ISI and Google unique Web/URL citations than Google total Web/URL citations (counting one site per site) Sample 1650 articles in 108 OA journals in eight disciplines: biology, chemistry, physics, computing, sociology, economics, psychology, education

Result 2 - 57% Sharing citations between ISI and GS (validating previous results) l l 57% (2, 387) of ISI citations were duplicated (overlapped) in Google Scholar results OR 43% Google Scholar citations were unique (covered in another study) l This overlap percentage was relatively higher in biology (66%), physics (62%) and computing (57%), and considerably lower in chemistry (33%). 882 articles in 39 OA journals in 4 disciplines= biology, chemistry, physics, computing.

Result 3 - Double growth in GS citations than ISI (validating GS) l The percentage increase for ISI citations was about 12% and Google Scholar 22% (October 2005 to January 2006) in four science disciplines. l This increase was considerably higher in computing (13% vs. 26%), biology, and physics; and it was significantly lower for chemistry (31% Vs. 18%) 882 articles in 39 OA journals in 4 disciplines= biology, chemistry, physics, computing.

Conference (43%) E-prints (48%) Journal (88%) Journal (68%) Result 4 - Type of GS unique citations differ in disciplines

Result 5 - Accessibility of GS unique citations l 70% of GS were full-text sources l Google Scholar has a wider coverage of Open Access (OA) web documents and non-journal documents more useful for citation tracking across full text documents

Result 6 - Classification of reasons for creating Web Citations in Science Identified Reasons Number % 365 23. 1 Informal Scholarly Reasons (CVs, scientific database, teaching, subject bibliographies, presentation file, discussion board) 779 49. 4 Navigational (Web Directories, mirror table of contents and papers, library links) 319 20. 2 Unknown (Not clear, missing pages) 114 7. 2 Scientific Related (journal, conference, citations, Cross. Ref, citation index) dissertation e-prints Sample of 1577 Google unique Web/URL citations in 64 open access journals from biology, physics, chemistry, and computing

Reasons for Creating Google Unique Web/URL Citations in the four science disciplines

Conclusion l l We can use Web based citation patterns for impact assessment of journals especially when ISI citations are not accessible and in social science disciplines with less ISI journal coverage. Disciplinary differences should be considered in the results.