|What is a citation count?|
A Citation Count is the number of times an article is cited by other articles. It is considered (by some) to indicate the quality of the article. If an article is cited often it must be an important or influential article. When using the Web of Science database or the Scopus database you can sort and display your search result by Times Cited so that the most highly cited work is displayed first.
An increasing number of databases include the citation count. Unfortunately this is rarely the total number of times an article has been cited because the citing article must be included in the database. For books and most conference proceedings citation counts in databases are considered incomplete. True citation counts would be higher than those given in the databases as no database lists all articles, books, book chapters, patents or conference proceedings and their references.
Different databases include different journals so the citation count of an article will be different in each database. Also the coverage of cited references begins in different years in different databases - for example - Scopus citation counts are not accurate for articles published before 1996. SciFinder citation counts are not accurate for articles published before 1997. Coverage begins earliest in the Web of Science. (Updated weekly)
When comparing citation counts it is important to remember that citation patterns are different in different disciplines.
Sometimes there are inaccuracies or variations in references. This means that they are not recorded in the citation count.
The Web of Science Cited Reference Search will search for inaccurate citations (or mis–cites) but you must use the first author of the paper to search for them. It will also search for cited articles and books or other items that are not published within the Web of Science coverage time span or not published in one of the journals indexed by the Web of Science.
|Creating citation reports|
Citation Reports in Web of Science and Citation Tracker in Scopus detail citation activity (including the h-index) of a search result. You can search for the publications and citation activity of an author, research group, or institution. You must be aware of the difficulties of comprehensively searching for the publications of an author or group. You can also see the citation activity of papers published in specific subject fields. (Updated weekly)
It is critical that citation counts be considered and compared only within a subject discipline as citation patterns vary greatly across disciplines.
Should you use the Web of Science or Scopus?
Web of Science
Help by Thomson Reuters
Series of 4 videos from Yale University on Citation Analysis (RECOMMENDED)
Help by Elsevier
Note: Both Citation Reports in Web of Science and Citation Tracker in Scopus allow you to remove self citations.
|Creating citation maps|
Citation maps in Web of Science give a colour coded visualization of the relationship between cited and citing references including second generation citations. For example – you have published a paper cited by 6 articles and these 6 articles have been cited by a further 18 articles. You can display these relationships and colour code them by author, institution, country etc. The analysis is at the paper level.
In this example a paper written in the US was cited by papers written in 5 different countries which were cited by papers written in 2 more countries. This paper has influenced 24 papers written in 7 countries.
Help by Thomson Reuters
Tutorial by Thomson Reuters
B.D. Simboli (2008) Review of Web of Science mapping tool. Issues in Science and Technology Librarianship, Summer 2008.
Google Scholar is the largest bibliographic database and it covers all types of literature not just journal articles, however from a citation indexing perspective it is considered difficult and lacking in transparency. It is difficult to count the number of publications of an author or group and how often they are cited because it is very time consuming to consolidate the many duplicates. However for some subject disciplines it is the only citation indicator available.
Pros and cons of computing the h-index using Google Scholar by Peter Jacso (2008)
The note in Lokman and Kiduk’s informative comparison of WoS, Scopus and GS on citation counts and ranking of 25 library and information science faculty members is sobering: ‘WoS data took about 100 hours of collecting and processing time, Scopus consumed 200 hours, and GS a grueling 3,000 hours [due to].. serious limitations of GS's document parsing and citation matching algorithms which are not so good in identifying authors and matching citations.’
SciFinder Web gives comprehensive coverage of all aspects of chemistry, as well as research in the biomedical sciences, engineering, materials science and agricultural science. Each CAS reference has citation counts but only if citing references are from CAS. The references that come from Medline do not have citation counts and do not contribute to citation counts. SciFinder citation counts are not accurate for articles published before 1997. There is no citation report or analysis for groups of citing references.
Publishers’ full text journal websites eg ScienceDirect, Highwire, Springerlink etc
|Citations in books|
Databases like Web of Science, Scopus and Google Scholar are useful for establishing how often a publication has been cited in the journal literature, but they cannot tell you how often it has been cited in books.
Does this matter? In many disciplines in the arts, humanities and social sciences, books are a very significant medium for publication of new research. Databases which only count citations in the journal literature are under-reporting the impact of publications in these disciplines.
It should be possible to check for citations to a particular publication in any database which includes the full text of books (in other words, any database of electronic books). The largest such database is Google Books, but it is far from comprehensive.
|What is the h-index?|
The h-index was first proposed by JE Hirsh as a measure of research impact of a scientist in 2005 An index to quantify an individual's scientific research output:
If your h-index is 15, you have 15 papers cited 15 times or more. If your h-index is 20, you have 20 papers cited 20 times or more. It is a measure of the number of publications published (productivity) as well as how often they are cited (impact): Productivity + Impact = Influence
Citation reports in Web of Science and Citation Tracker in Scopus calculate the h-index of a search result. You can search for the publications of an author, research group, or institution and calculate the h-index. You must be aware of the difficulties of comprehensively searching for the publications of an author or group. No database lists all articles.
Help Web of Science (scroll up for full details) by Thomson Reuters
Help Scopus by Elsevier
Citation Analysis for a Known Author (RECOMMENDED) by Yale University
Use the h-index measure with care. Citation patterns vary across disciplines. h-indices in Medicine are much higher than in Mathematics for example. Researchers in different disciplines can not be compared using the h-index.
Even within the same discipline the h-index should not be used alone as a measure of research quality. Consider the following 3 researchers who have all published 10 papers and all have an h-index of 5.
There are many variations of the h-index. Some take into account the number of co-authors, another the years the author has been publishing etc. You can see a quick summary or more detailed information about the h-index and variations.
Statistical comparison of the h-index and variations of the h-index by Panaretos & Malesios: Assessing scientific research performance and impact with single indices
How to boost your h-index
An irreverent look at the h-index by James R. Williamson My h-index Turns 40: My Midlife Crisis of Impact
|Benchmarking using citation counts|
It is possible to compare the citation counts of individual scientists, schools or research institutes, universities and even countries. When benchmarking there are a couple of golden rules:
Always ask: Do the results make sense?
Benchmarking can be at a number of different levels Ahmed and Rafiq (1998):
Ahmed, P. K. and Rafiq, M. (1998) Integrated Benchmarking: a Holistic Examination of Select Techniques for Benchmarking Analysis. Benchmarking for Quality Management and Technology, 5 (3), pp. 225–242.
Essential Science Indicators (ESI) can be used to benchmark within broad subject disciplines (based on Web of Science data). You can answer questions:
FAQ on benchmarking papers by Thomson Reuters
Benchmarking papers Help by Thomson Reuters
Tutorial: Using Baselines in Essential Science Indicators: Learn how to put citation data into context using baselines from Essential Science Indicators. (Thomson Reuters)
FAQ on benchmarking universities. (Thomson Reuters)
|Benchmarking using other Bibliometric Analyses|
Most databases allow you to analyse the search result. PubMed users can use PubReMiner. Most allow you to analyse by author, year published, journal, and keyword or subject category.
Web of Science and Scopus automatically analyse a search on a topic by
For a search of an author’s work you can analyse by
For a search of citations to an author’s work you can analyse by
Citation mapping allows you to analyse up to 2 generations of cited and citing references by author, year, journal, institution, and country.