Farrokh Habibzadeh, MD,
Secretary, World Association of Medical Editors (WAME)
Editorial Consultant, The Lancet
Vice President, Eastern Mediterranean Association of Medical Editors (EMAME)
Director, NIOC Medical Education and Research Center, Shiraz, Iran
Scientometrics (Definition)
 Scientometrics is the science of
measuring and analyzing science.
 It is often done through bibliometrics.
Scientometrics
 First citation analysis by Gross &
Gross (1927)
 Journal to journal cross-citation
(Cason & Lubotsky, 1936)
 Journal Impact Factor (IF) by
Eugene Garfield (1955)
Journal Impact Factor
n
 Definition:
C
IF 
P
IFi 
C
k 1
k ,i
Pi
• IF: IF of journal in 2008
• P: number of substantive articles published in 2006-07
• C: number of citations made in year 2008 to articles published in
2006-07
Garfield E. JAMA; 295(1); 90-3
Example
Top Journals in General/Internal Medicine
Journal Impact Factor
 Is calculated and sold by Thomson-Reuter (formerly
Thomson Scientific, before that, the Institute of Scientific
Information [ISI])
 No one has independently audited the validity of the data*
 In many centers, affects
 Decision on where to publish
 Whom to promote or hire
 Success of grant applications
 Winning prize
 Even salary bonuses
*Rossner M, van Epps H, Hills E. J Exp Med 2007;204:3052-3
Journal Impact Factor
 Pros
 A measure for journal quality
 Easy to calculate
 Cons
 Substantive articles?
 May be used unwisely

“drawing conclusions about individual performance is not the proper
way to interpret impact factor.”*
 Calculations behind the wall†
 Subject to manipulation‡
*http://scientific.thomsonreuters.com/citationimpactforum/8424440/
† Rossner M, van Epps H, Hills E. J Exp Med 2007;204:3052-3.
‡ Marusic
A, et al. Science and Engineering Ethics 2008;14:41-9.
H-index
 A scientist has index h, if h of his/her Np papers
have at least h citations each, and the other (Np − h)
papers have no more than h citations each.
Hirsch JE. Proc Nat Acad Sci 2005;102:16569–72.
Example
8
7
Number of Citations
6
5
4
3
2
1
0
1
2
3
4
5
Paper
6
7
8
H-index
 Pros
 Two-dimensional
 Cons
 Who?
 Different databases!
 Contribution through one or two influential papers

Nikolai Korotkoff

Wilhelm Conrad Röntgen
 Subject to manipulation
 Self-citation
 Member of a prolific research group
4
6
Journal Network
Weighted Impact Factor
 Counting a reference from a more prestigious journal
more heavily
 Kochen, 1974
 Pinski & Narin, 1976
 PageRank of Google™
 Y-factor (Bollen, et al, 2006)
 SCImago SJR (www.scimagojr.com, 2007)
 Prestige: “the standing or estimation in the eyes of
other people”/journals
(Merriam-Webster Dictionary)
Journal Impact Factor
n
 Definition:
C
IF 
P
IFi 
C
k 1
k ,i
Pi
• IF: IF of journal in 2006
• P: number of substantive articles published in 2004-05
• C: number of citations made in year 2006 to articles published in
2004-05
Garfield E. JAMA; 295(1); 90-3
Weighted Impact Factor
n
WIFi 
w
k 1
k ,i
Pi
 Ck ,i
Calculation of Weights
 Popularity of the cited journal
 Prestige of the citing relative to the cited journal
Calculation of Weights
10.00
PYIFk
qk ,i 
PYIFi
6.00
weight
8.00
4.00
q
1  0.828  e k ,i
wk ,i  10 2.00
 qk ,i
1
1  16.183  e
q

w
[0, +)  [0.1, 10)
PYIF: Previous year IF
0.00
0.00 1
5.00
quotient
10.00
How Journals Are Cited
IF
WIF
1.346
2.703
SWISS MED WKLY
1.333
3.723
J TRAVEL MED
14.780
7.410
ANN INTERN MED
22.4
25.8
26.1
25.8
23.175
8.869
JAMA-J AM MED
ASSOC
22.7
23.9
27.8
25.6
63.4
18.3
34.8
39.1
13.2
7.1
5.1
19.0
IF
51.296 14.472
NEW ENGL J MED
21.6
23.3
28.5
26.7
<1
1.0-2.5
13.750 14.475
2.501-5
PLOS MED
33.4
0%
20%
10.7
40%
19.6
36.3
60%
Percentage of Citations
80%
>5
100%
Parameters of 70 Medical Journals
Rank
Abbreviated Journal Title
NEW ENGL J MED
Articles
Published in
2004-05
624
Total Cites
Received in
2006
32,009
IF
51.296
WIF
14.472
Year 2006
IF
1
WIF
2
2
4
LANCET
776
20,021
25.800
9.078
3
5
JAMA-J AM MED ASSOC
674
15,620
23.175
8.869
4
6
ANN INTERN MED
364
5,380
14.780
7.410
5
1
PLOS MED
108
1,485
13.750
14.475
6
3
ANNU REV MED
59
781
13.237
10.593
7
10
BRIT MED J
910
8,413
9.245
5.934
15
32
ANN FAM MED
142
540
3.803
3.803
29
8
AMYLOID
67
128
1.910
6.763
39
67
J AM BOARD FAM MED
137
208
1.518
1.518
42
50
SWISS MED WKLY
191
257
1.346
2.703
43
33
J TRAVEL MED
138
184
1.333
3.723
67
70
DM-DIS MON
47
35
0.745
0.729
70
69
CAN FAM PHYSICIAN
117
82
0.701
1.222
Weighted Impact Factor (WIF)
100
PLOS MED
ANNU REV MED
10
NEW ENGL J MED
LANCET
AMYLOID
ANN INTERN MED
JAMA-J AM MED ASSOC
1
DM-DIS MON
WIF = 0.28 IF + 3.03
Spearman's rho = 0.78, n = 70
0
0
1
10
Impact Factor (IF)
100
Other Metrics
 Immediacy Index
Jevin West
Ben Althouse
 Eigenfactor™ score
 Article Influence™ score
Martin Rosvall
 Per article citation influence
Carl Bergstrom
Ted Bergstrom
Top Journals in General/Internal Medicine
F1000 Medicine