OR must be in all capital letters or it will be ignored. Somebody
doing research on cancer may want their search strategy to
look like this: cancer OR neoplasm OR tumor.
Google Scholar does understand parentheses that are used
in search statements. Much like in addition and multiplication
problems, the parentheses force Google Scholar to combine
search terms in a specific way. For example, someone look-
ing for information on colon cancer might want to type colon
AND (neoplasm OR cancer OR tumor). If the searcher does
not use parentheses and capitalized Boolean terms, then he
or she might get articles about the colon as well as articles on
other types of cancer, cluttering their results on colorectal neo-
plasms. Searchers who don’t want any articles on rectal cancer
can use the minus symbol (hyphen) to eliminate the word
rectal. The search phrase would look like this: colon (neoplasm
OR cancer OR tumor) -rectal. (There are dangers, of course, in
such a strategy. The word rectal could be mentioned briefly in
an article that otherwise would meet the searcher’s needs.)
Google Scholar’s advanced search function enables searchers
to look for specific authors, publications, titles, date ranges,
and subject areas. Any search result can be turned into an
automated e-mail alert to be notified of new papers.
Limitations
Unlike other databases, Google Scholar does not actually con-
tain any full text articles or abstracts. Instead, it data mines
websites and uses its algorithms to display the search results.
Therefore if the information that Google Scholar finds is incor-
rect, then the search results will be incorrect. In the past,
Google Scholar’s server has had some problems correctly
identifying authors, titles, and journals. The article “Google
Scholar’s Ghost Authors” by Peter Jasco describes how Scholar’s
crawling techniques misidentified many authors of articles as
“subscribe” or, in the case of a Lancet article, “fabricated the
first initials and the last name of the first author from the sub-
title of another paper and the second author’s name from the
title of a third paper.”
2
While it appears Scholar has addressed
some of the indexing issues, it still seems to have problems. As
recently as February 2013, blogger Karen Blakeman reported
Google Scholar erroneously listed an author as “MA Lib”
instead of the correct author K. Fraser.
3
Since Google Scholar
factors the number of times a paper has been cited to help
build the list of relevant results, Google Scholar’s ghost authors
may affect search results.
Citation searching is a helpful way to supplement a Google
Scholar subject search. Simply click on the “cited by” link to
see the authors who cited that specific work. Although the cita-
tion searching is helpful, it is important to know that this can
be easily manipulated artificially. In the article, “Manipulating
Google Scholar Citations and Google Scholar Metrics: simple,
easy and tempting,” researchers reported that they could arti-
ficially increase an article’s display rank by uploading fake
papers to the Web that are discovered by Google’s Web crawl-
ers. Their experiment resulted in an increase of 774 citations
for 129 papers.
4
While there hasn’t been a documented case
of somebody manipulating citations to increase their article’s
ranking, it is important to be aware of as other databases such
as PubMed, Web of Science, and Scopus are not as vulnerable
to this type of manipulation.
Several recent studies have found that searching Google
Scholar can be helpful and yield interesting and relevant
results. For quick clinical research, Google Scholar can be quite
effective. A study of nephrologists seeking information for clin-
ical questions found “Google Scholar returns twice as many
relevant articles as PubMed and provides greater access to
free full-text articles.”
5
Scholar may be effective for quick clini-
cal questions, but it may not be as effective for other search
queries. The authors of an article in Systematic Reviews found
Google Scholar’s article retrieval “too low” to be used as a
single database for conducting systematic reviews.
6
No database is perfect; every database has its strengths and
weaknesses when it comes to indexing, structure, and cover-
age. To find comprehensive information on a subject, search-
ers must look at a variety of databases. Because each database
is created differently, it is essential to know how those differ-
ences affect searching and to adjust the search strategy accord-
ingly. Google Scholar is a very helpful database and can serve
as a great additional tool for retrieving articles.
Author disclosure: The author notes that she has no commercial associ-
ations that may pose a conflict of interest in relation to this article.
Author contact: kraftm@ccf.org
References
1. Hightower C, Caldwell C. Shifting Sands: science researchers on Google
Scholar, Web of Science, and PubMed, with implications for library
collections budgets. Issues in Science and Technology Librarianship 2010.
www.istl.org/10-fall/refereed3.html. Accessed February 4, 2014.
2. Jasco P. Google Scholar's ghost authors. Library Journal 2009; http://
www2.hawaii.edu/~donnab/lis670/lj_print.pdf. Accessed February
4, 2014.
3. Blakeman K. Google Scholar author fail. 2013; www.rba.co.uk/
wordpress/2013/02/04/google-scholar-author-fail/.
4. Lopez-Cozar ED, Robinson-Garcia N, Torres-Salinas D. Manipulating
Google Scholar citations and Google Scholar metrics: simple, easy and
tempting. 2012. http://arxiv.org/abs/1212.0638
5. Shariff SZ, Bejaimal SA, Sontrop JM, et al. Retrieving clinical evidence: a
comparison of PubMed and Google Scholar for quick clinical searches.
J Med Internet Res. 2013;15(8):e164.
6. Bramer WM, Giustini D, Kramer BM, Anderson P. The comparative recall
of Google Scholar versus PubMed in identical searches for biomedical
systematic reviews: a review of searches used in systematic reviews.
Systematic reviews. 2013;2(1):115.
FIND
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