Citation searching and bibliometrics

Olof DannbergAlnarp Library

Agenda

• Citation searching – an introduction• What is bibliometrics?• Web of Science• What is Journal Impact Factor?• Journal Citation Reports• Criticism of IF and some alternatives

Bibliometrics

“statistical analysis of books, articles, or other publications”

(The Oxford Dictionary of English)

Bibliometrics

• Citation analysis in one method used in bibliometrics

• By analyzing citations at article level you can estimate the popularity and impact of specific articles and authors

• By counting citations at journal level you can calculate the Journal Impact Factor

Exercise: Web of Science

1. Do a search on your own subject (one or two keywords only)

2. Sort by Times Cited

3. How many times has the most cited research article been cited?

4. Did you know about this article before?

h-index

Hirsch-index

The value of h is equal to the number of papers (n) in the list that have n or more citations

Example:

An h-index of 4 means that that you have 4 articles that have been cited at least 4 times.

Exercise: Web of Science

1. Which article by an Alnarp researcher is the most cited? 

2. Use Author Finder to find all articles by your supervisor (or yourself) 

3. What is the h-index?

Exercise: Scopus

1. Do a search on your own subject (one or two keywords only)

2. Sort by citations

3. Is the most cited article the same as in Web of Science?

4. Has it been cited by other scientific web sources (theses, dissertations etc)?

Impact Factor

IF =Citations in 2009 (to articles published 2007-2008)

Articles published 2007-2008

Ohter JCR measures

• 5-Year Impact Factor• The impact factor calculated for 5 years instead of 2

• Immediacy Index• How many times articles have been cited within one year.

Indicates which journals are publishing “hot” articles

• Cited Half-Life• The median age of the journal’s articles cited in the current

JCR year. Indicates the long-term value of the articles

Exercise: Journal Citation Reports

1. Select to view all journals in your own subject area

2. Which journal has the highest Impact Factor in this subject?

3. Did you expect this journal to be in top?

Criticism of IF

Coverage• English language bias• Books are not included

Subject differences• Citation behavior varies between subject areas

Methodological flaws• Negative citations• Self-citations• Misprints and title changes

Misuse • Authors and editors manipulate the IF by strategic publishing and in-house citations

Alternatives: journal level

Eigenfactor• Includes more sources, not only journal articles

•Measures citations to articles published in the last 5 years

•Citations from highly-ranked journals are given a higher value, similar to Google’s PageRank algorithm

Alternatives: journal level

SCImago Journal Rankwww.scimagojr.com

• Based on citation data from Scopus• Measures citations to articles published in the last 3 years

• Uses a Google-like ranking algorithm, just like the Eigenfactor

• Example:SCImago Journal Rankings

SCImago vs. JCRSCImago SJR Journal Citation Reports IF

1 Cell 13,754 1 CA-A Cancer Journal for Clinicians 87,925

2 Nature Genetics 13,236 2 Acta Crystallographica Section A  49,926

3 Annual Review of Immunology 11,815 3 New England Journal of Medicine 47,050

4 CA-A Cancer Journal for Clinicians 11,298 4Nature Reviews Molecular Cell Biology

34,284

5 Annual Review of Biochemistry 9,947 5 Annual Review of Immunology 37,902

6Annual Review of Cell and Developmental Biology

8,650 6 Physiological Reviews 37,726

7 Cancer Cell 8,360 7 Chemical Reviews 35,957

8 Nature 8,016 8 Nature 34,480

9 Annual Review of Neuroscience 7,652 9 Nature Genetics 34,284

10 Immunity 7,611 10 Reviews of Modern Physics 33,145

49 New England Journal of Medicine 3,337 12 Cell 31,152

99 Acta Crystallographica Section A  1,925

Exercise: SCImago

1. Look at the journal rankings in your own subject area

2. Compare with the Impact Factor in JCR

3. Are there any differences?

Alternatives: article level

Usage statistics• Open Access journals often use download statistics as an indicator

• BioMed Central www.biomedcentral.com

• PLoSwww.plos.org

Alternatives: article level

Faculty of 1000 f1000.com• Qualitative evaluation• Evaluates the most important articles in biology and medicine

• Researchers and clinicians rates and comment on papers they read

• Example:f1000.com/3509957

Summary

• Citation searching is useful as an alternative to keyword searching

• Bibliometrics give you comparable quantitative data about scientific publications

• The usefulness and reliability of the methods have been questioned

• New methods for evaluation have arisen, quantitative and qualitative, but have yet to gain wider acceptance as replacement for citation counts and Impact Factor

Further readings

• SLU University Library (2010). Bibliometrics. Accessible: http://www.slu.se/en/library/publish/eindex/

• Vice-chancellor's decision about affiliation ... 2010-01-02 (Swedish)

• Garfield, E. (1994). The concept of citation indexing : a unique and innovative tool for navigating the research literature. Accessible: http://thomsonreuters.com/products_services/science/free/essays/concept_of_citation_indexing/

“Not everything that can be counted counts, and not everything that counts can be counted”

Albert Einstein