Farrokh Habibzadeh, MD, Vice President, World Association of Medical Editors (WAME) Honorary Editor, The Lancet ME Editorial Consultant, The Lancet Founding Editor, The IJOEM Director, NIOC Medical Education and Research Center, Shiraz, Iran 1
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 J p ( ) y Eugene Garfield (1955) 2
Journal Impact Factor Definition: C IF = P IF: IF of journal in 2006 IF i = n k= 1 C P i ki, 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 2006;295; 90 3 3
Example Top Journals in Cardiology 4
Journal Impact Factor Is calculated and sold by Thomson Reuter (formerly Thomson Scientific, before that, the Institute of Scientific Information [ISI]) In many centers, affects Decision on where to publish Whom to promote or hire Success of grant applications Winning prize Even salary bonuses No one has independently audited the validity of the data* *Rossner M, van Epps H, Hills E. J Exp Med 2007;204:3052 3 5
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 p way to interpret impact factor. * Calculations behind the wall Subject to manipulation *http://scientific.thomsonreuters.com/citationimpactforum/8424440/ Rossner M, et al. J Exp Med 2007;204:3052 3. Marusic A, et al. Science and Engineering Ethics 2008;14:41 9. 6
Citations to Am J Cardiol Impact Factor 2009: 3.575 3575 SEARCH STRATEGY Database: Web of Knowledge (ISI) Publication Name=(American Journal of Cardiology) AND Year Published=(2009) Refined by: Document Type=(ARTICLE OR REVIEW) RESULTS 1889 records 946 articles and reviews Minimum: 0; Maximum: 60 Mean (SD): 3.3 (5.1); Median (IQR): 2 (5) Skewness: 3.7 Distribution of Citations 7
Citations to Articles in 2009 SEARCH STRATEGY Database: Web of Knowledge (ISI) Address=(Shiraz) AND Address=(Iran) AND Year Published=(2009) Refined by: Subject Areas=(CARDIOVASCULAR SYSTEM & CARDIOLOGY) AND Document Type=(ARTICLE) RESULTS Total 1414 78 Cardiovascular 56 Articles Distribution of Citations 8
H index A scientist has index h, if h of his/her N p papers have at least h citations each, and the other (N p h) papers have no more than h citations each. Hirsch JE. Proc Nat Acad Sci 2005;102:16569 72. 9
H index = 5 H index = 3 10
H index = 7 11
H index = 6 H index Pros Two dimensional Cons Who? Different databases! Contribution ti through h one or two influential l papers Nikolai Korotkoff Wilhelm Conrad Röntgen Subject to manipulation Self citation Member of a prolific research group 12
H index and its variants Bornmann L, et al. J Am Soc Info Sci Technol 2008;59:830 7. Article No Citations Author 1 Author 2 1 80 7 2 60 6 3 50 5 4 50 5 5 50 5 6 4 2 7 3 2 8 2 1 9 0 0 10 0 0 Total 299 33 Zhang CT. PLoS ONE 4(5): e5429. doi:10.1371/journal.pone.0005429. 13
Journal Network 14
Weighted Impact Factor Counting a reference from a more prestigious i 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) www.scimagojr.com 15
Top Journals in Cardiology 16
SJR vs JIF Sicilia MA, et al. J Informetrics 2011; doi:10.1016/j.joi.2011.01.007 17
Journal Impact Factor Definition: C IF = P IF: IF of journal in 2006 IF i = n k= 1 C P i ki, 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 2006;295;90 3 18
Weighted Impact Factor WIF i = n k= 1 w ki, ki, P i C Calculation of Weights Popularity of the cited journal Prestige of the citing relative to the cited journal 19
Calculation of Weights 10.00 q w [0, + ) [0.1, 10) w ki, q ki, weight 8.00 PYIFk = PYIF 6.00 i 4.00 q, 1 0.828 e ki = 10 2.00 qki, 1+ 16.183 e 1 0.00 1 0.00 5.00 10.00 quotient PYIF: Previous year IF How Journals Are Cited IF WIF 1.346 2.703 SWISS MED WKLY 63.4 18.3 13.2 51 5.1 1.333 3.723 J TRAVEL MED 34.8 39.1 7.1 19.0 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 51.296 14.472 NEW ENGL J MED 21.6 23.3 28.5 26.7 IF <1 1.0 2.5 13.750 14.475 PLOS MED 33.4 10.7 19.6 36.3 2.501 5 >5 0% 20% 40% 60% 80% 100% Percentage of Citations 20
Parameters of 70 Medical Journals Rank Articles Published in Total Cites Received in Year 2006 IF WIF Abbreviated Journal Title 2004 05 2006 IF WIF 1 2 NEW ENGL J MED 624 32,009 51.296 14.472 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 1.222 100 Weighted Impact Factor (WIF) 10 1 AMYLOID PLOS MED ANNU REV MED ANN INTERN MED LANCET NEW ENGL J MED JAMA-J AM MED ASSOC DM-DIS MON WIF = 0.28 IF + 3.03 Spearman's rho = 0.78, n = 70 0 0 1 10 100 Impact Factor (IF) 21
Other Metrics Eigenfactor score Article Influence score Per article citation influence Jevin West Ben Althouse Martin Rosvall Carl Bergstrom Ted Bergstrom Top Journals in Cardiology 22
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