SCI期刊影响因子分析

×JCR is not for evaluating individuals/papers
Recognize skewed nature of citation data
• Citation distributions are not normal (the typical bell-shaped curve) • Apparent at every level of analysis • Citation distributions are extremely skewed: few papers or people are cited at high frequency, most cited little
50 years ago…
Garfield, E. “Citation indexes for science: A new dimension in documentation Cited References association of ideas of its author through association of ideas.” Science, 122 Indexes p.108-111, (3159), Citation July 1955. new approach to subject control
Why Impact Factor?
• Comparison of scholarly journals – Journal collection development in a library – Decision-making support for article submission by a researcher – Editorial policy development by a journal publisher • Problems in SIMPLE comparison of citation counts – Size (# of articles published in a year) – Frequency (# of issues published in a year)
of the literature of science
2004
2003
Times Citedຫໍສະໝຸດ 2003Cited References
2004
2001
Paper/Article
1998
Citing papers
2000
1993
Cited References
How to define “citation”?
Journal Impact Factor
• Average citation count in a particular year • Assigned at “journal level” • Assigned to journals indexed in Citation Indexes – SCIE (Science Citation Index Expanded) – SSCI (Social Sciences Citation Index) • Included in Journal Citation Reports® database • Updated annually • Helpful when evaluating a journal’s relative importance • Not intended to evaluate individual papers/researchers
Journal Citation Reports 2004 Science Edition
The journal impact factor is a measure of the 2004 IF frequency with which the "average article" in =38.570 a journal has been cited in a particular year. The impact factor will help you evaluate a journal's relative importance, especially when you compare it to others in the same field.
366 papers published in 2003
14549+14147
28696
＝
378+366 744
≒ 38.570
Impact Factors only take the recent 3 years into consideration. What about the fields with a longer citation span?
Times Cited: How many articles are citing this article (350 articles)
Look up journal info in JCR
What you can tell in Journal Citation Reports®
• Which journals publish most number of articles? • Which journals are most cited in particular disciplines? • Which journals have “high impact” in particular disciplines? • Which journals publish “hot” topics? • Journal’s self-citations • Review article rates • Cited-citing relationships of journals
Article-level vs. Journal-level data
Journal Citation Reports
独特的多学科期刊分析评价工具
自1997年以来的数据：


提供基于引文数据的期刊评价指标
显示出引用和被引期刊之间的相互关系 帮助用户以定量的方式了解全球的学术期刊
利用JCR on Web深入了解学术期刊
67% papers are below the average
Web of Science, search conducted on Sept 28, 2005
Misuse of “Impact Factor”
I first mentioned the idea of an impact factor in 1955. At that time it did not occur to me that impact would one day become the subject of widespread controversy. …… It has been used constructively to select the best journals for Current Contents® and the Science Citation Index,® and for library collections. However, it has been misused in many situations, especially in the evaluation of individual researchers.
Impact Factor: AVERAGE citation count
Web of Science® record example
Records are counted at journal-level, then included in Journal Citation Reports®
Cited References: Items cited by this article (29 items)
Essential Science IndicatorsSM
Web of Science
Science Citation Index Expanded Social Sciences Citation Index
Essential Science Indicators
Counted by scientist, country, institution, journal
Web of Science® and its offspring
Web of Science Journal Citation Reports
Stats by journal
Journal Impact Factor
Research Services Group
National Science Indicators Institutional Citation Reports Topic Citation Reports etc…
期刊影响因子分析
汤姆森科技信息集团 中国办事处
Citation and citation analysis Journal Citation Reports - Journal impact factor
Essential Science Indicators
Citation Analysis via Peer Assessment
Essential Science Indicators
Baselines
Web of Science® and its offspring
Web of Science Journal Citation Reports
Stats by journal
Journal Impact Factor
Science Citation Index Expanded
• 科学期刊在同行科学家的交流中起着根本的作用。即科学文献能够代 表科学活动以及表现不同分支学科之间关系。在整个期刊系统中，可 以区分出“重要”的国际性期刊 • 学术文献被重要的期刊文献引用的次数是这一文献的影响或国际显著 性的一种度量
• Moed et al., The use of bibliometric data for the measurement of university research performance, Research Policy, 14, 131149,1985; • Oppenheim, C. Journal of Documentation, 1995
“The use of JCR and JPI in measuring short and long term journal impact”. Presented by Eugene Garfield at Council of Scientific Editors Annual Meeting held in May 9, 2000. /papers/cseimpactfactor05092000.html
Calculation of Journal Impact Factor
Example: 2004 Impact Factor for New England Journal of Medicine
2002
378 papers published in 2002
2003
2004
14549 times cited in 2004 14147 times cited in 2004
引文分析的前提
利用引文分析进行科研评估的理论基础: Normative Perspective on citations 美国社会学家罗伯特· 默顿 (Robert K. Merton): 《科学的规范结构》 文献引用的动机 Citation motivation: 原文献的科学价值 Citation – Impact, Influence, Importance, Performance