PubMed and Google Scholar are accessed for free... Scopus offers
about 20 per cent more coverage than Web of Science, whereas Google
Scholar offers results of inconsistent accuracy. PubMed remains an
optimal tool in biomedical research. Scopus covers a wider journal
range...but it is currently limited to recent articles (published after
1995) compared with Web of Science. Google Scholar, as for the web
in general, can help in the retrieval of even the most obscure informa-
tion but its use is marred by inadequate, less often updated, citation
information.
(Falagaset al.2008: 342)9.2 Using Hirsch’s h-index
There are different ways to measure a researcher’s impact. Although ideally
there would be many different indicators that assess the impact and quality
of a publication, there is one indicator that has become more or less the
standard in bibliometry; Hirsch’s (2005) h-index, defined as:
A scientist has index h if h of his/her Np papers have at least h citations
each, and the other (Np-h) papers have no more than h citations each.In other words: a researcher has an h-index of 15 if 15 of her publications
have been cited at least 15 times.
There are a number of variants of the h-index that remedy some of the
disadvantages of this index, such as its age-relatedness. Some authors will
continue to“harvest”an increasing h-index even when they have stopped
publishing, since their earlier publications continue to be cited. An example
in our database is Eric Kellerman, who produced a number of publications
that are still cited, even though he switchedfields from AL to professional
photography and his most recent publication dates from 1997. Another dis-
advantage is that the h-index of a researcher can never go down. This can to
a certain extent be remedied by looking at specific windows of time, e.g. total/
last ten years/lastfive years.
For the current project it was decided to use the h-index as one of the
indicators of impact. To calculate the h-indices, two citation analysis systems
have been used: Google Scholar Citations (http://scholar.google.com) and
Harzing’s Publish or Perish (www.harzing.com). For GS the h-index can be
found easily when a researcher has a profile in Scholar. For example, Batia
Laufer’s profile, as presented in Table 9.1 and Figure 9.1, shows her indica-
tors (h and i10) in total and since 2009, and the development of her citations
over time. Her profile page shows the list of her publications with the
number of citations per publication. The i10 index is the number of pub-
lications that have been cited at least ten times. This indicator will not be
used further in the analyses.
108 The citation game