<P> Each database is likely to produce a different h for the same scholar, because of different coverage . A detailed study showed that the Web of Science has strong coverage of journal publications, but poor coverage of high impact conferences . Scopus has better coverage of conferences, but poor coverage of publications prior to 1996; Google Scholar has the best coverage of conferences and most journals (though not all), but like Scopus has limited coverage of pre-1990 publications . The exclusion of conference proceedings papers is a particular problem for scholars in computer science, where conference proceedings are considered an important part of the literature . Google Scholar has been criticized for producing "phantom citations," including gray literature in its citation counts, and failing to follow the rules of Boolean logic when combining search terms . For example, the Meho and Yang study found that Google Scholar identified 53% more citations than Web of Science and Scopus combined, but noted that because most of the additional citations reported by Google Scholar were from low - impact journals or conference proceedings, they did not significantly alter the relative ranking of the individuals . It has been suggested that in order to deal with the sometimes wide variation in h for a single academic measured across the possible citation databases, one should assume false negatives in the databases are more problematic than false positives and take the maximum h measured for an academic . </P> <P> Little systematic investigation has been done on how the h - index behaves over different institutions, nations, times and academic fields / disciplines . Hirsch suggested that, for physicists, a value for h of about 12 might be typical for advancement to tenure (associate professor) at major (US) research universities . A value of about 18 could mean a full professorship, 15--20 could mean a fellowship in the American Physical Society, and 45 or higher could mean membership in the United States National Academy of Sciences . </P> <P> For the most highly cited scientists in the period 1983--2002, Hirsch identified the top 10 in the life sciences (in order of decreasing h): Solomon H. Snyder, h = 191; David Baltimore, h = 160; Robert C. Gallo, h = 154; Pierre Chambon, h = 153; Bert Vogelstein, h = 151; Salvador Moncada, h = 143; Charles A. Dinarello, h = 138; Tadamitsu Kishimoto, h = 134; Ronald M. Evans, h = 127; and Axel Ullrich, h = 120 . Among 36 new inductees in the National Academy of Sciences in biological and biomedical sciences in 2005, the median h - index was 57 . However, he points out that values of h will vary between different fields . </P> <P> Among the 22 scientific disciplines listed in the Thomson Reuters Essential Science Indicators Citation Thresholds (thus excluding non-science academics), physics has the second most citations after space science . During the period January 1, 2000--February 28, 2010, a physicist had to receive 2073 citations to be among the most cited 1% of physicists in the world . The threshold for space science is the highest (2236 citations), and physics is followed by clinical medicine (1390) and molecular biology & genetics (1229). Most disciplines, such as environment / ecology (390), have fewer scientists, fewer papers, and fewer citations . Therefore, these disciplines have lower citation thresholds in the Essential Science Indicators, with the lowest citation thresholds observed in social sciences (154), computer science (149), and multidisciplinary sciences (147). </P>

Who has the highest h index in medicine