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Web of Science: Citation Analysis and Impact Factors
- 1. Web of Science Joost Daams, MA Arnold Leenders Ingeborg Nagel, MSc Medical Library
- 2. Programme • Introduction to Citation Analysis and Web of Science • Web of Science (WoS) – Searching for articles – Cited reference search – Analyzing results • Hirsch-index (H-index) • Journal Citation Reports (JCR): impact factors Medical Library
- 3. Introduction: What is a citation index? • A citation index is an index of citations between publications, allowing the user to easily establish which later documents cite which earlier documents1. • First citation index was the Science Citation Index, established in 1960 by the Institute for Scientific Information (ISI). Later followed by the Social Sciences Citation Index and the Arts and Humanitites Citation Index. • Examples of citation indexes: Web of Science, Scopus, CiteSeer, Google Scholar. 1 "Citation index," in Wikipedia; available from http://en.wikipedia.org/wiki/Citation_index Medical Library
- 4. Time Cited articles Citing articles 1950 2010 original work 2000 2002 2007 2012 1997 2006 2008 1962 2007 2012 Related articles 1998 2001 Medical Library
- 5. Introduction: citation analysis Use citation analysis to find: • Who has cited your work • Most cited articles on your research topic • Leading researchers, institutions and journals in your field of research Medical Library
- 6. Introduction: Web of Science content (1) • Combination of 3 citation databases: – Science Citation Index – Social Sciences Citation Index – Arts & Humanities Citation Index • Over 12,000 journals and 120,000 conference proceedings indexed, coverage to 1975. • Citation analysis tool Medical Library
- 7. Introduction: Web of Science content (2) • Multidisciplinary • Medicine and • 12000 journals related fields • No controlled vocabulary • 5400 journals • Conference proceedings • MeSH terms • Citation analysis • Clinical filters Medical Library
- 8. Introduction: recap • Citation analysis • Web of Science: content Medical Library
- 9. WoS: Searching for articles (1) • Combine search terms using operators: – AND, OR, NOT – NEAR/x (x = number of words that separate terms) – SAME (terms in same field, can only be used in Address field) • Topic field = Title, Abstract, Author Keywords • Combine search sets on the Search History page Medical Library
- 10. WoS: Searching for articles (2) • Phrase search: "kidney transplant" • Both right- and left-hand truncation: – transplant* finds transplant, transplants, transplantation – *saccharide finds disaccharide, polysaccharide, etc. • Lemmatization (on/off) includes synonyms, plurals, and singulars in the search results. Does not apply for terms enclosed in quotation marks (" "). Medical Library
- 11. WoS: Searching for articles (3) • Find articles on Fabry disease • Sort articles by time cited • Which article has been cited most and how many times was this article cited? Medical Library
- 12. WoS: Searching for articles (4) Assignment 1. Searching for articles on a topic Go to the Web of Science database and search for articles on the topic delirium in patients with hip fracture. Sort the results by "Times Cited – highest to lowest". a. Which article has been cited most and how many articles have cited this article? b. Click on the Times Cited number to view all articles that cited the selected article. What is the title of the most recent articles that cited it? Medical Library
- 13. Cited reference search (1) Medical Library
- 14. Cited reference search (2) Assignment 2. Cited reference search Go to the Cited Reference Search tab in Web of Science and search for the following article, using the predefined fields Cited Author, Cited Work and Cited Year. a. How many additional citing articles do you find for this article by using the Cited Reference Search option? b. Why were these articles not recognized as being citing articles by the Web of Science? Medical Library
- 15. Additional: create a citation alert When you create a citation alert, you are notified by e-mail whenever the document has been cited by a new publication. The alert is active for one year. You may renew the alert at any time.
- 16. WoS: Analyzing results (1) • Who is the leading author or institution in your field of research? • In which journal should you publish? • How has research on a topic developed over time? • Analyze references by: o Author o Organization o Country o Journal title o Publication year Medical Library
- 17. WoS: Analyzing results (2) A Citation Map shows the citation relationships (cited references and citing articles) between a selected paper and other papers. Medical Library
- 18. WoS: Analyzing results (3) Medical Library
- 19. WoS: Analyzing results (4) Assignment 3. Analyzing results Go to the Search History tab in Web of Science to return to the results from exercise 1. Analyze the results to find: a. Which author had published most articles on delirium after hip fracture. b. Which journal (Source Title) has published most articles on this topic. c. Which country is leading in this field of research. Medical Library
- 20. H-index (1) 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: An index to quantify an individual's scientific research output. Proc Natl Acad Sci U S A 2005;102:16569-16572.) Medical Library
- 21. Web of Science: recap • Searching for articles • Cited reference search • Analyzing results Medical Library
- 22. H-index (2) The h-index (Hirsch-index) is an index that attempts to measure both the productivity and impact of the published work of a scientist or scholar. The index is based on the set of the scientist's most cited papers and the number of citations that they have received in other publications In the AMC the h-index is one of the factors used for the scientific evaluation of the Principal Investigators Medical Library
- 23. a: n publications c: n citations h: h-index c h h a Medical Library
- 24. H-index : 4 10 c 5 h h 0 5 10 15 a Medical Library
- 25. h-index : 4 h-index : 4 10 c 5 h h 0 5 10 15 a Medical Library
- 26. H-index (3) Important: Articles n a>h are of no interest for calculating the h-index! Medical Library
- 27. H-index (4) How to calculate the h-index: • In the AMC: use the Web of Science • Two ways to calculate – Author search – Search option using the author index Medical Library
- 28. Calculate the hirsch-index of mrs. A.H. Teeuw General paediatrician Emmakinderziekenhuis Amsterdam Medical Library
- 29. H-index (5) Problems: • Spelling of the author's name differs (initials) • Different authors have the same name • Unknown where the author has worked (even for the author) • Faulty citations Medical Library
- 30. H-index (6) Assignment 4. Calculate the Hirsch-Index of the scientists: a. Tabbers M; paediatric gastroenterologist AMC b. Your promotor Medical Library
- 31. JCR – Impact Factors (1) • What it is … JIF2011 = A/B A = the number of times articles published in 2009 and 2010 were cited by indexed journals during 2011. B = the total number of "citable items" published by that journal in 2009 and 2010. ("Citable items" are usually articles, reviews, proceedings, or notes; not editorials or Letters-to-the-Editor.) • Application evaluate research performance job promotion make decisions on funding evaluate journal collections determine publication strategy Medical Library
- 32. H-index: recap • What it’s for • What it is • How to calculate Medical Library
- 33. JCR – Impact Factors (2) • Critique Temporality bias Geographical/language bias Topicality bias Incentive for self-citations Range of provided subject topics Assignment of journals to topics Poor adaptation of web downloads / web citations Non-transparent journal inclusion criteria by Thomson Reuters Monolithic organisation • Strengths “ Impact factor is not a perfect tool to measure the quality of articles but there is nothing better and it has the advantage of already being in existence and is, therefore, a good technique for scientific evaluation. (…) The use of impact factor as a measure of quality is widespread because it fits well with the opinion we have in each field of the best journals in our speciality.” (Hoeffel C. Journal Impact factors. Allergy. 1998;53;1225) Medical Library
- 34. JCR – Impact Factors (3) Some JIF-derivatives (relevant for determining publication strategy): • “Journal Ranking” and “Quartile in Category” • Aggregate Impact Factor • Median Impact Factor • Immediacy Index Medical Library
- 35. JCR – Impact Factors (5) Assignment 5. 1. What is the 2011 impact factor of The Lancet? 2. Let’s pretend you’re about to send your manuscript to one of the top- ranked IF journals in your discipline (≈ category). One of your colleagues suggests the Journal of NeuroEngineering and Rehabilitation a. What is the 2011 impact factor of this journal? b. Describe in plain language what your answer under 2a expresses c. Explain why your decision to send your manuscript to this journal could depend on whether you are a neuroscientist or a physiotherapist. Hint: take into account the journal’s category score. 3. What is the 2009 impact factor of Aids Care? 4.Does the official IF address self cites? Medical Library
- 36. JCR – Impact Factors: recap H – Index & JIF quizz: True or False? H-Index JIF Describes journal impact Describes author impact Based on fixed source data Is adjusted for publication type (i.e. letter to the editor versus systematic review etc.) Is adjusted for self citation (resp. of own publications and own journal) Allows for interdisciplinairy benchmarking Medical Library
Notes de l'éditeur
- The journal Impact Factor is the average number of times articles from the journal published in the past two years have been cited in the JCR year.
- The aggregate Impact Factor for a subject category is calculated the same way as the Impact Factor for a journal, but it takes into account the number of citations to all journals in the category and the number of articles from all journals in the category. An aggregate Impact Factor of 1.0 means that that, on average , the articles in the subject category published one or two years ago have been cited one time. The median Impact Factor is the median value of all journal Impact Factors in the subject category. The Impact Factor mitigates the importance of absolute citation frequencies. It tends to discount the advantage of large journals over small journals because large journals produce a larger body of citable literature. For the same reason, it tends to discount the advantage of frequently issued journals over less frequently issued ones and of older journals over newer ones. Because the journal impact factor offsets the advantages of size and age, it is a valuable tool for journal evaluation. The Immediacy Index is the average number of times an article is cited in the year it is published. The journal Immediacy Index indicates how quickly articles in a journal are cited.The aggregate Immediacy Index indicates how quickly articles in a subject category are cited. The Immediacy Index is calculated by dividing the number of citations to articles published in a given year by the number of articles published in that year.Because it is a per-article average, the Immediacy Index tends to discount the advantage of large journals over small ones. However, frequently issued journals may have an advantage because an article published early in the year has a better chance of being cited than one published later in the year. Many publications that publish infrequently or late in the year have low Immediacy Indexes.For comparing journals specializing in cutting-edge research, the immediacy index can provide a useful perspective.
- 1,684 [problemen: ander jaar dan standaard jaar, ander JCR segment dan Science, problemen met de ondertitel waardoor aids care ongetrunceerd bij title words bijv. niet wordt gevonden] 2a. 3,264 [let op: JCR science edition!] 2b. On average 3,264 times articles from “Journal of NeuroEngineering and Rehabilitation” published in the past two years have been cited in 2011. 2c. Two ways: - journal ranking -> quartile score - subject categories -> select and compare both relevant subject categories: “view category data”. Compare for instance the median impact factors in relation to the journal’s IF. 3. No – this figure is provided in the section “Journal Self Cites” of the journal record in JCR.