Reference publication year spectroscopy (RPYS) of Eugene Garfield’s publications
Reference publication year spectroscopy (RPYS) of Eugene Garfield's publications
Lutz Bornmann 0 1 2
Robin Haunschild 0 1 2
Loet Leydesdorff 0 1 2
Eugene 0 1 2
Robin Haunschild 0 1 2
0 Amsterdam School of Communication Research (ASCoR), University of Amsterdam , PO Box 15793, 1001 NG Amsterdam , The Netherlands
1 Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart , Germany
2 Division for Science and Innovation Studies, Administrative Headquarters of the Max Planck Society , Hofgartenstr. 8, 80539 Munich , Germany
Which studies, theories, and ideas have influenced Eugene Garfield's scientific work? Recently, the method reference publication year spectroscopy (RPYS) has been introduced, which can be used to answer this and related questions. Since then, several studies have been published dealing with the historical roots of research fields and scientists. The program CRExplorer (http://www.crexplorer.net) was specifically developed for RPYS. In this study, we use this program to investigate the historical roots of Eugene Garfield's oeuvre.
Cited references; Garfield; Historical roots; Reference publication year spectroscopy; RPYS; Pioneer; Bibliometrics
Bibliometrics has become a central component of research evaluation. Field-normalized
indicators are used to assess the scientific performance of institutions and countries.
Individual researchers are well informed about their h index. The development to this
prominence of bibliometrics had not been possible without the groundbreaking work of
Eugene Garfield (EG). EG conceptualized citation indexing in science and published the
underlying concept in Science
. His invention of the index ‘‘revolutionized
the world of scientific information and made him one of the most visionary figures in
information science and scientometrics’’
(van Raan and Wouters 2017)
. In the 1960s, he
started the professional use of bibliometrics by founding the Institute for Scientific
Information (ISI) (now Clarivate Analytics, see clarivate.com). He developed the Science
Citation Index, the Social Sciences Citation Index, and the Arts and Humanities Citation
Index. These indexes are predecessors of the Web of Science (WoS) which is well-known
today to scholars
(Small 2017; Wouters 1999b)
. During EG’s lengthy career, he published
more than 1500 publications (see www.researcherid.com/rid/A-1009-2008).
In this study, we are interested in the roots of EG’s oeuvre. Which studies, theories, and
ideas have influenced EG’s own scientific work?
Marx et al. (2014)
publication year spectroscopy (RPYS), which can be used to answer this and related
questions. In recent years, several studies have been published dealing with the historical
roots of research fields. For example,
deals with the historical roots of citation
analysis in a recent study. Thor et al. (2016a) developed the CRExplorer—a program
specifically designed for RPYS (http://www.crexplorer.net). In the study, we use this
program to investigate the historical roots of EG’s oeuvre.
The study is based on papers published by EG. We used his ResearcherID to collect his
publications and added some further publications which are not covered by the
ResearcherID. The dataset consists of n = 1558 papers published between 1954 and 2016
(containing 15,890 cited references, CRs). The papers have been retrieved from the WoS.
The downloaded files were imported in the CRExplorer for further processing
(Thor et al.
. The removing, clustering, and merging functionalities of the CRExplorer have
been used to clean the CR dataset, especially for variants of the same CR. The clustering
and merging of variants (using volume and page number information) lead to a slightly
reduced set of CRs (n = 15,850). A further 199 CRs were deleted because the
bibliographic information was unprecise (for example, no reference publication year, RPY, was
provided). We formed two datasets from this initial set for the RPYS:
Dataset including self-citations by EG We deleted those CRs which have
occurrences of less than 10% in a single year (i.e. the share of occurrences for a
CR among the occurrences of all CRs in one year is less than 10%). This step leads
to the first set of 328 CRs. Note that this also removes two of the most referenced
CRs with n = 100 and n = 97 occurrences as their share of occurrences in their
RPYs is 9.9 and 8.3%, respectively. However, there are a number of CRs which
appeared in Current Contents without a volume number; so they do not provide
useful bibliometric information (see below).
Dataset without self-citations We deleted all self-cited publications (n = 1283).
Since the CR data in the WoS only contains the first author name, the identification
of self-citations is restricted to this first name. As above, we deleted those CRs
which have occurrences of less than 10% in a single year (see above). This step
results in the second final set of 316 CRs. Although the difference between data set 1
and data set 2 (12 CRs) appears to be rather small at a first glance, the spectrogram
changes significantly. Most self-cited CRs (n = 1271) are removed due to the
occurrence threshold of 10% in a single year.
The 1558 papers authored by EG were published in 125 different journals, but 68.2% of his
papers were published in Current Contents. In the 1950s, Current Contents has been
founded by EG as a rapid alerting service
. The first subject edition covered
biology and medicine. Other subject editions were added later, and the original version was
renamed into Current Contents Life Sciences. Initially, Current Contents consisted of
printed versions of reproduced title pages of major peer-reviewed journals. An author
index with addresses and a subject index were provided as well. This indicates that EG’s
publications in Current Contents have a status different from papers in peer-reviewed
journals. Similarly, EG founded The Scientist as a professional magazine for scientists in
1986. Although this journal was also incorporated into the Science Citation Index, it does
not contain references and is thus only registered for being cited; including a Journal
Impact Factor (JIF) of 0.369 in 2015.
Table 1 shows the journals in which EG has published at least 10 papers. The journals
shown contain 88.6% of EG’s publication output.
EG has published most of his papers (80.9%) between 1970 and 1990. During these two
decades, he has published 60 papers per year on average. However, 77.8% of the papers
during this time frame were published in Current Contents. The unusual distribution of
EG’s papers across journals and publication years shows that EG has been an unusual
scientist preferring a journalistic medium.
Without the publications in Current Contents and The Scientist, EG’s oeuvre is 257
publications in scholarly journals containing 2244 references. Figure 1 compares the
citations to EG’s full and scholarly oeuvre. The two papers in Science of 1955 and 1972 are
heavily cited. The erratic blue-colored curve is mainly citation of Current Contents and to
a large extent self-citation. The peak in 2006 is an article in JAMA entitled ‘‘The history
and meaning of the journal impact factor’’.
We discuss the other important CRs using Table 3 which shows the CRs with the largest
number of occurrences within data set 2 (without self-citations). On the first glance, we can
observe significantly lower numbers of occurrences for the CRs. Thus, these publications
were less important for EG to write his papers than his own publications. The CRs in
Table 3 can be divided into three groups: (1) bibliometrics, (2) biology, and (3)
The group of CRs related to bibliometrics is the largest group in Table 3 with five CRs
(the fifth, seventh, eighth, ninth, and tenth CR). The group of CRs which belong to the field
of biology is only slightly smaller with four CRs (the first, second, fourth, and eleventh
CR). The smallest group of CRs which belongs to non-scholarly material is composed of
Garfield, E., 1955, Citation indexes for science—new dimension in 1955 61
documentation through association of ideas. Science, 122(3159), 108–111
Garfield, E., 1971, Current Contents, P5 1971 54
Garfield, E., 1972, Citation analysis as a tool in journal evaluation: journals can 1972 64
be ranked by frequency and impact of citations for science policy studies.
Science, 178(4060), 471–479
Garfield, E., 1972, Current Contents, 1101, P5 1972 57
Garfield, E., 1973, Current Contents, P5 1973 73
Garfield, E., 1974, Current Contents, P5 1974 61
Garfield, E., 1975, Current Contents, P5 1975 79
Garfield, E., 1978, Current Contents, P5 1978 88
Garfield, E., 1985, Current Contents, V43, P3 1985 75
Garfield, E., 1987, Current Contents, P3 1987 62
Garfield, E., 1988, Current Contents, P3 1988 54
The CRs which are responsible for the large peaks in Fig. 2 are shown
Beyond doubt, EG has been one of the most influential scientists in the field of
bibliometrics. The field would perhaps not exist, if EG had not introduced the idea of indexing
citations for quantitative analyses in the history and philosophy of science
(Elkana et al.
1978; Gingras 2016; Wouters 2000)
. EG created the fundament on which all empirical
studies in bibliometrics are based. In addition to the idea of citation indexing, he initiated
several lines of research in bibliometrics later on. For example, the development of
indicators based on bibliometric data started with the introduction of the JIF
2006; Garfield and Sher 1963)
. Since this initial introduction, the development of several
(advanced) indicators followed in bibliometrics which do not only refer to journals (several
journal-based indicators can be found in Clarivate Analytics’ Journal Citation Report), but
also to other entities (e.g., to single researchers with the h index).
EG was the first who formulated a list of possible reasons why documents are cited in
(Bornmann and Daniel 2008)
. Thus, he started the discussion in bibliometrics
about the meaning of citations and the formulation of underlying theoretical approaches. A
further example of his groundbreaking work is the introduction and development of
(Garfield 2004; Garfield et al. 1964; Leydesdorff 2010)
method which can be applied by using the historiographic software HistCiteTM ‘‘facilitates
the understanding of paradigms by enabling the scholar to identify the significant works on
a given topic’’
(Garfield et al. 2003, p. 400)
. Similar software, which has been developed
on this base later on, are CitNetExplorer
(http://www.citnetexplorer.nl, see van Eck and
(www.crexplorer.net, see Thor et al. 2016a, b)
This study deals with EG’s roots (studies, theories, and ideas) and how they are reflected
in EG’s publications. We used the CRExplorer—which has its roots in EG’s own software
developments—and applied RPYS to his publication set. The results show that EG has
cited his own publications in many cases. This can be possibly traced back to the fact that
EG was a pioneer not only in shaping the citation index, but also in many lines of research
in bibliometrics. Furthermore, inspiring inputs might have been come from
noncitable sources. For example, Shepard’s Citations is a citation index which is used in US
legal research. It lists all authorities who cite particular cases, statutes, or other legal
authorities. EG later acknowledged that his citation index was heavily influenced by
. However, this does not reflect in (or cannot be
retrieved from) his citations, because there does not exist a paper on Shepard’s Citations
which could be cited in this context.
Among the papers most referenced by EG are some non-scholarly publications, some
publications from the early evolving field of bibliometrics, and publications from other
disciplines for the presentation of examples. The heterogeneity of the cited publications
demonstrates the wide-spreading interests of EG which range from the historiography of
science as an empirical operationalization for questions in the history and philosophy of
(e.g. Elkana et al. 1978; Gingras 2016)
, citation indexing as an approach to
document retrieval (Garfield 1955), journal evaluation for library management
1950; Garfield 1957, 1972)
, the mapping of the sciences
(Garfield 1987; Small and Garfield
, to bibliometrics and the theory of citation
(Garfield 1975, 1979)
The prevailing publication and citation of non-scholarly publications makes clear that
EG’s interests are not limited by scholarly bounds. They reach beyond the narrow
definitions of scientific epistemological interests and perform the translation of the latter into
Acknowledgements Open access funding provided by Max Planck Society.
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