An over view of various bibliometric indicators, how they are computed, and where they can be found.

1. BASIC CITATION
METRICS:
AN OVERVIEW

2. WHAT DO BIBLIOMETRICS
MEASURE?
Eugene Garfield
“Father of Citation Analysis”
• Scholarly communication: tracing the history
and evolution of ideas from one scholar to
another
• Measures the scholarly influence of articles,
journals, scholars, institutions
Photo: http://www.chemheritage.org/Discover/Collections/Oral-Histories/Details/asset_upload_file66_69008_thumbnail.jpg

3. SOURCES OF
CITATION
DATA AT
UALBANY
• UAlbany subscription is 1993-present
• Pre-1993 data is available in print volumes – Ask A Librarian!
• Currently covers over 12,000 journals
• Journals undergo quality review process prior to inclusion
• Weak in conference proceedings, books, data repositories
• Master Journal List of Web of Science

4. • Many subject specific
databases also include cited
reference information.
• There will be overlap in
coverage of different
databases on a cover, take
care to identify/remove
duplicate citations.
• See Subject Specific
Databases on this guide for
more information on these
resources.
SOURCES OF
CITATION
DATA

5. • Journal coverage unknown, sporadic
– Whatever the web crawler can “read”
• No quality control process
• Better coverage of
– conference proceedings
– foreign language articles
– Nontraditional publication sources (blogs, reports, white papers)
– Theses and dissertations
• Coverage roughly from 1996-present; some older but inconsistent
SOURCES OF
CITATION
DATA

6. • Citation data overlaps in all
sources, but not completely
• Unique citing references in
all databases
• Unique metrics developed
using each major database
WHAT’S THE
DIFFERENCE?

7. • Citation Count
• Journal Impact Factor
• Eigenfactor
• H-index
• SNIP
• SJR
METRICS

8. • Number of times cited in
scholarly journals indexed in a
particular resources
• Citation count metric does
not take into account:
– Materials not included in
citation database
– Sometimes self citations
are eliminated from count
CITATION
COUNT

9. • Found in: Web of Science –
Journal Citation Reports
• Essential concept: “how fast
are ideas spreading from this
journal to other
publications?”
• Formula:
JOURNAL
IMPACT
FACTOR
Number of citations to a journal in a given year
from articles occurring in the past 2 years,
divided by the number of scholarly articles
published in the journal in the past 2 years

10. Journal of Hypothetical ExamplesJOURNAL
IMPACT
FACTOR
Citing references appearing in
2010, to articles published in
Journal in 2009 and 2008
100
200
Total number of articles in
Journal published in 2009
and 2008
0.50 JIF

11. • Cannot be used to compare
across disciplines
• Two year time frame not
adequate for social sciences,
humanities
• Coverage of some disciplines
not sufficient in Web of
Science
• Is a measure of “impact” a
measure of “quality”?
CONCERNS
WITH JIF

12. • Found in:
– eigenfactor.org
– Web of Science: Journal
Citation Reports
• Essential concept: Takes into
account the total amount of
“citation traffic” appearing in
JCR
• Formula:
EIGENFACTOR
Influence of the citing journal,
Divided by the total number of citations
appearing in that journal.

13. • Journal Impact
Factor:
– All citing references weighted
equally
• Eigenfactor:
– SOME CITING REFERENCES ARE
MORE IMPORTANT THAN OTHERS
• The citing articles from
journals that are heavily cited
themselves demonstrate
greater influence
ESSENTIAL
DIFFERENCES:
JIF &
EIGENFACTOR

14. • Eigenfactor will always be
bigger if a journal is larger,
i.e., publishes more articles
• Article Influence Score:
corrects for journal size
– takes the journal’s
Eigenfactor score and
further divides it by the
number of articles in the
journal.
– Correlated to the JIF
CONSIDER
THE
FOLLOWING

15. H-INDEX
http://proj.ncku.edu.tw/research/commentary/e/20080815/images/0808110317430yfDpK.jpg
• Found in:
• Many citation analytics sources
• Web of Science
• Google Scholar Citations
• Etc…
• Essential Concept: Identifies a
sustained record of multiple
publications that have been cited
frequently
• Formula:
The maximum number of articles h, such
that each has received at least h citations.
Jorge E. Hirsch

16. 0
5
10
15
20
25
30
1 2 3 4 5 6 7
NumberofCitations
Article Number
H-index
Scholar A
Scholar B
H-INDEX
EXAMPLE
Scholar A Scholar B
10 27
10 12
9 5
8 4
7 4
6 2
6 2
56 citations 56 citations
6 h-index 4 h-index

17. • Found in:
– www.journalmetrics.com
– Scopus
• Essential concept: Citation
Potential: total number of
citing references in all journals
which have cited this journal
• Formula:
SNIP:
SOURCE
NORMALIZED
IMPACT PER
PAPER
The ratio of the journal’s average citation count
per paper to the citation potential in its subject
field

18. • Can compare SNIP scores
across disciplines
• Aggregate of a journal, so
larger journals automatically
have higher scores than
smaller journals
PROS AND
CONS OF SNIP

19. • Found in:
– www.scimagojr.com
– Scopus data
• Essential Concept: measures “current
average prestige per paper”
• Formula:
SJR: SCIMAGO
JOURNAL
RANKING
Prestige factors include: # of journals in the
Scopus database, # of articles in Scopus from
this journal, citation count, eigenvector
analysis of important citing references,
corrections for self-citations, and
normalization by the number of significant
works published in the journal.

20. • Corrects for self citations
• Correlated to JIF
• Scores can be compared
across disciplines
• Web version provides
data on countries
• Three year window not
good for social sciences
PROS AND
CONS OF SJR

21. • Journal quality ≠ article quality
• Citing a work ≠ agreement with
that work
• Self citations: including them is
controversial
• Variance in citation patterns
from domain to domain
KEEP IN MIND

22. • Is a trend analysis of scholarly
influence over time needed, or
simply a count of total citations?
• Does the database adequately
cover the key journals in my
subject domain?
• Are there significant works in my
domain that are not peer
reviewed, scholarly journals
(such as conference proceedings,
government reports, etc.)
KEEP IN MIND