pcplantdb

["Lawrence F. London, Jr." <lfl@intrex.net>]

<http://scientific.thomson.com/knowtrend/essays/citationindexing/concept/>


Knowledge & Trends : Essays : Citation Indexing : The Concept of 
Citation Indexing: A Unique and Innovative Tool for Navigating the 
Research Literature

        

THE CONCEPT OF CITATION INDEXING: A UNIQUE AND INNOVATIVE TOOL FOR 
NAVIGATING THE RESEARCH LITERATURE

This essay was originally published in the Current Contents print 
editions January 3, 1994
Introduction

This is my first Current Contents® (CC®) essay under the rubric of 
Citation Comments. As discussed in last week's CC, this new monthly 
feature will focus on the applications of the Institute for Scientific 
Information®'s (ISI's) databases. 1 An appropriate topic to launch this 
new series is perhaps the most rudimentary -- the basic concept of 
citation indexing.

To start, it is important to clarify the terminological distinction 
between "citation" and "reference". In his classic book Little Science, 
Big Science, Derek Price gave a clear definition of both terms. He said: 
"It seems to me a great pity to waste a good technical term by using the 
words citation and reference interchangeably. I therefore propose and 
adopt the convention that if Paper R contains a bibliographic footnote 
using and describing Paper C, then R contains a reference to C, and C 
has a citation from R. The number of references a paper has is measured 
by the number of items in its bibliography as endnotes, footnotes, etc., 
while the number of citations a paper has is found by looking it up [in 
a] citation index and seeing how many others papers mention it." 2 (p. 284)

In a nutshell, citations symbolize the conceptual association of 
scientific ideas as recognized by publishing research authors. 3 By the 
references they cite in their papers, authors make explicit linkages 
between their current research and prior work in the archive of 
scientific literature. These conceptual associations have been described 
by Robert Merton, Manfred Kochen, and other scholars as intellectual 
transactions, formal acknowledgments of "intellectual debt" to an 
earlier source of information. 4, 5 That is, explicit references imply 
that an author has found useful a particular published theory, method, 
or other finding.

ISI's databases index these intellectual transactions by listing both 
the cited and citing works. (That is, the cited work is a paper or book 
that has been mentioned in the references of other works, while the 
citing work is the one that contains the references.) The citation 
indexes were originally designed primarily for information retrieval. 
Mainly but not exclusively through citation connections, the databases 
enable you to navigate the literature in unique ways. As a result, you 
are able to locate relevant papers independent of language, title words, 
or author keywords. A variety of citation-based search strategies are 
available, including bibliographic coupling or linking of papers through 
shared references (Related Records®) 6, KeyWords Plus® ,7 8, and others.
Unique Advantages of Citation Indexes

The ISI® databases differ from traditional indexing and abstracting 
services in several ways. From the outset, the Science Citation Index® 
(SCI®), Social Sciences Citation Index® (SSCI®), and Arts & Humanities 
Citation Index® (A&HCI®) have been multidisciplinary. They cover 
virtually all disciplines whereas traditional services are limited to a 
single field.

The advantages of a multidisciplinary index can be exemplified by the 
work of Nobelist Harold C. Urey. Published in Science in 1962, "Lifelike 
forms in meteorites" described the chemical compounds they contained 
that were essential to the formation of life on earth under the right 
conditions. 9 This paper deserved to be indexed in a variety of 
single-discipline databases. But more importantly, citations to this 
paper have appeared in a large variety of journals in astrophysics, 
biology, cosmology, chemistry, earth sciences, geochemistry, and so on.

ISI's indexes are also comprehensive, providing complete coverage of all 
types of published source items--not just original research papers, 
review articles, and technical notes but also letters, corrections and 
retractions, editorials, and other items. ISI studies have shown that 
these latter items are important, have substantial impact, and provide 
useful links to scientific issues and controversies.

As stated at the outset and perhaps most importantly, ISI uniquely 
indexes the references cited by these source items. This gives you the 
ability to perform prospective as well as retrospective searches of the 
literature. Like other indexes, ISI's databases allow you to move back 
in time to locate previously published papers. But ISI's databases 
uniquely allow you to move forward in time--to determine who has 
subsequently cited an earlier work. Thus, by starting with a single 
paper or book, you can identify whatever additional papers have referred 
to it. And each retrieved paper, in turn, may provide a new list of 
references with which to continue the citation search.
Authoritative, Timely, In-Depth Access to the Literature

It is important to stress that the citation-based associations and 
connections within the literature are made by authors themselves. 
Traditional indexes typically rely on human subject specialists to 
categorize and describe papers, usually using controlled vocabularies or 
thesauri.

A potential drawback of the latter method is illustrated in my early 
experience in compiling a list of references on "general adaptation 
syndrome." Out of a sample of papers published in a five-year period, 23 
had cited Hans Selye's primordial paper. 10 But even though all 23 were 
indexed in Index Medicus, not one was listed under the MeSH heading, 
"Adaptation."

Another shortcoming of human indexing is that there is an inevitable 
delay due to the time required to read or scan the papers and make 
subjective judgments about relevant descriptors. In short, timeliness is 
reduced. In contrast, citation indexing does not involve this type of 
analysis, which enables the SCI, SSCI, and A&HCI to be virtually 
concurrent with the literature.

In addition, due to the expense of human indexing, traditional indexes 
limit the number of terms. But in ISI's citation indexes, all cited 
references are indexed. Since the typical research paper today contains 
from 25 to 35 references, the resulting number of index entries is 
correspondingly high. Indeed, citing papers provide useful indexing 
"statements" or descriptors through the papers they cite.
Citations as Indexing Statements

Thanks to a suggestion by Chauncey Leake in the 1950s, I conducted a 
thorough analysis of review articles and their cited references. By 
doing what today would be called context analysis, I soon discovered 
that the sentences in the review articles were actually detailed, 
descriptive indexing statements about papers or books they cited.

Several years before ISI® was founded, this basic notion was further 
developed with Robert L. Hayne when we both were at Smith, Kline and 
French Labs in the 1950s. Through large test samples, we concluded that 
the titles of papers cited in reviews and other articles were sufficient 
to add useful descriptive words and phrases to the citing paper. This 
was later confirmed in studies by A. J. Harley, as Irv Sher and I 
recently reported.11, 12

In 1990, ISI was able to introduce this citation-based method of 
derivative (algorithmic) subject indexing, called KeyWords Plus®. 7, 8 
In addition to title words, author-supplied keywords, and/or abstract 
words, KeyWords Plus supplies words and phrases to enhance these other 
descriptors and thereby retrievability. These KeyWords Plus terms are 
derived from the titles of cited papers, which have been algorithmically 
processed to identify the most-commonly recurring words and phrases.
Conclusion

In the space available, it is not possible to stress all the innovative 
advantages of citation indexing for information retrieval or to 
illustrate in detail the variety of search strategies it makes possible. 
While future Citation Comments will address these topics, it is perhaps 
more important to stress here why scientists should get into the habit 
of literature searching. One of the more obvious reasons is to avoid the 
unwitting duplication of research and the wasted time, effort, and funds 
this involves.

For example, in 1964, John Martyn, Aslib Research Department, London, 
showed how unintentional duplication is related to ignored or missed 
sources in the literature.13 He surveyed about 650 British scientists 
and asked if they had later discovered information in the literature 
they wished they had at the beginning of their projects. Twenty-two 
percent said yes and cited 245 specific instances. Of these, 18 percent 
involved unintentional research duplication. And in 43 percent of these 
instances, the researchers felt that time, money, or work was wasted.

I've always believed that authors should be held by journal editors to 
the same "due diligence" standards required of inventors by patent 
offices. That is, authors should formally assert and verify that their 
ideas are original and do not replicate discoveries already reported in 
the archives. Consequently, they should be required to acknowledge the 
"prior art" that directly or indirectly influenced their research.

In my opinion, the problem begins with teaching. Too few colleges 
require undergraduates to learn how to search the literature. But with 
proper mentoring, students should come to graduate schools already 
conditioned to do "prior art" searching--and practice these techniques 
throughout their careers, whether in academia or industry.

Dr. Eugene Garfield
Founder and Chairman Emeritus, ISI
References

1. Garfield E. From Current Comments® to Citation Comments: continuing a 
31-year series of Current Contents® essays with a new focus. Current 
Contents (51/52):3-5, 20-27 December 1993.

2. Price D. J. D. Little science, big science...and beyond. New York: 
Columbia University Press, 1986. 301 p.

3. Small H. G. Cited documents as concept symbols. Soc. Stud. Sci. 
8:327-40, 1978.

4. Merton R. K. Foreword. (Garfield E) Citation indexing--its theory and 
application in science, technology, and the humanities. Philadelphia: 
ISI Press®, 1983. p. vi.

5. Kochen M. How do we acknowledge intellectual debts? J. Doc. 43:54-64, 
1987.

6. Garfield E. Announcing the SCI® Compact Disc Edition: CD-ROM gigabyte 
storage technology, novel software, and bibliographic coupling make 
desktop research and discovery a reality. Current Contents® (22):3-13, 
30 May 1988. (Reprinted in: Essays of an information scientist: science 
literacy, policy, evaluation, and other essays. Philadelphia: ISI 
Press®, 1990. Vol. 11. p. 160-70.)

7. ---------- KeyWords Plus®: ISI®'s breakthrough retrieval method. Part 
1. Expanding your searching power on Current Contents on Diskette®. 
Current Contents (32):5-9, 6 August 1990. (Reprinted in: Ibid., 1991. 
Vol. 13. p. 295-9.)

8. ----------KeyWords Plus takes you beyond title words. Part 2. 
Expanded journal coverage for Current Contents on Diskette includes 
social and behavioral sciences. Current Contents (33):5-9, 13 August 
1990. (Reprinted in: Ibid., 1991. Vol. 13. p. 300-4.)

9. Urey H. C. Lifelike forms in meteorites. Science 137:623-8, 1962.

10. Selye H. General adaptation syndrome. J. Clin. Endocrinol. 
6:117-230, 1946.

11. Gray W. A. & Harley A. J. Computer assisted indexing. Inform. 
Storage Retrieval 7:167-74, 1971.

12. Garfield E. & Sher I. H. KeyWords Plus--algorithmic derivative 
indexing. J. Amer. Soc. Inform. Sci. 44:298-9, 1993.

13. Martyn J. Unwitting duplication of research. New Sci. 21:338, 1964.