Getting started with bibliometrics / impact factor analysis Search guide • • • •
These resources will help you find information relating to bibliometrics You can locate the most highly cited journals in your field Identify the most highly cited journal articles Find Information on the research output of specific authors: their average number of citations, number of papers published and who has cited them.
ISI Journal Citation reports Content • • • •
ISI Journal Citation reports provides information on the most frequently cited journal titles in individual scientific and social science subject fields. This is produced by analyzing data taken from over 5,900 journals in science and technology and 1,700 in the social sciences It enables you to quickly find information on leading journal titles in a subject field Compare the impact of individual titles in a subject field Data is usually updated annually. Currently the LSE has access to editions from 1998 onwards. These contain data from 1989-2009.
Access • • • •
To access the database search for the title (ISI Journal Citation Reports) on the LSE library catalogue Expand the catalogue record and click on the online links Field. Click on the title of the resource. Access using your LSE Network username and password. Once you have logged onto the main ISI database click on the yellow tab Select a database then choose Journal citation reports. Once you have logged onto the database you will need to select either the sciences or social sciences edition. If you are not sure which one to choose tick the box next to one of the options and then View a group of journals by subject area this will display the full list of subject categories in each. An interesting fact to note is that sometimes very similar subject areas (but with different rankings of journals appear in the science and social science sections. This is because the Science section is drawn from journals indexes in the ISI Science Citation Index and the social Science edition uses the slightly different Social Sciences Citation Index. It is therefore important to cite which one you have used for your analysis) Once this is selected you need to choose the year. Note the database is usually updated annually.
Search options. •
To find data on the most important titles in you subject area. Select the edition, the year and then the option View a group of journals by subject category. This will display a list of more detailed subjects. It is possible to select one subject by highlighting it and then
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clicking submit. This will display the rankings for that subject. If you want to select and compare 2 or more subject areas use the control key and highlight the subjects you need before submitting. To search for rankings for an individual title select the search for a specific journal option then enter the full or abbreviated title. Note on the right hand side of the screen there is the option to view any journal title name changes for the last two years.
Understanding and refining your Search results • • • •
There are a number of different ways you can choose to sort your data results. You can view it arranged alphabetically or by a number of different rankings. (These are explained below the diagram) A typical research results screen looks like this. Note that the number of titles ranked differs between subjects. All results refer to the JCR year i.e. all data refers to journals published in that year. This may differ from a calendar year.
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Abbreviated journal title This option provides access to the full journal title and a number of other detailed data options. These are described fully in the section Journal information below. Total cites: The total number of times that the journal has been cited by titles included in the ISI database. Note it could possibly have been cited by titles not in the database or in other years.
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Impact Factor A useful means of evaluating the importance of a journal in a particular subject field. It counts the average number of times articles published in the journal have been cited in the JCR year. The 5 year impact factor presents the number of times articles from the journal published in the last 5 years have been cited in the JCR year. It is calculated by dividing the number of citations by the total number of articles published during the period of 2 years (impact factor) or 5 years (5 year impact factor). Therefore an impact factor of 1.0 means that on average the articles published have been cited once. Aggregate impact factor – allows some cross comparison with levels of citation from other journals in the discipline. It considers average number of citations by subject category taking into account all the journals in the JCR category and the total number of articles published in them. Immediacy Index another possible measure of the importance of a journal. It measures how quickly the average article in a journal is cited by recording the average number of citations in the year it is published. It is calculated by dividing the number of citations to articles published in a given year by the number of articles published in that year. Articles The total number of articles published in the journal in the given year. Cited half-life The average age of the articles that were cited from this journal in the current year. It is calculated by measuring the number of years from the current publication year for 50% of the citations. For example in the table above, in JCR 2006 the journal American Economic Review has a cited half-life of more than 10 This means that 50% of all citations to articles from that journal in 2008 were to articles published more than 10 years ago The Eigenfactor Score a relatively new measure developed by University of Washington biologist Carl T. Bergstrom which measures the number of times articles from the journal published in the past five years have been cited in the JCR year. o It differs from other measures in that counts citations to journals in both the sciences and social sciences. o Eliminates self-citations. Every reference from one article in a journal to another article from the same journal is discounted. o Weights each reference according to a stochastic measure of the amount of time researchers spend reading the journal. o Further information can be found at http://www.eigenfactor.org/ it is also discussed more fully later in this guide under the heading other methods. o The Article Influence Score calculates measures the relative importance of the journal on a per-article basis. It is the journal's Eigenfactor Score divided by the fraction of articles published by the journal. That fraction is normalized so that the sum total of articles from all journals is 1. The mean Article Influence Score is 1.00. A score greater than 1.00 indicates that each article in the journal has above-average influence. A score less than 1.00 indicates that each article in the journal has below-average influence.
Understanding and using the journal information pages. •
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Each journal title in the database has its own page of information where you can view publisher details and detailed statistical graphs. These can be viewed by searching for a specific journal title or from the results screen of a subject category search by clicking on the abbreviated journal title. A typical journal information screen looks like this.
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This screen also offers the option to view some of the statistical data in graphs and tables. Cited Journal view data on journals which cited this title for the last 10 years. Citing Journal view data on journals cited by articles in this journal for the last 10 years. Selfcites provides information on the contribution of self citations (articles published within the journal itself) to its impact factor. Source Data view information on the type of articles published in the journal. It provides data on the total number of original research articles compared to review articles (book reviews etc.) Plus the total of number of references cited by articles published in the journal in a given year.
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A graph which shows impact factor data for the journal for the last 10 years. This enables you to make a clearer judgement about its rising or declining importance in the discipline over a longer time span.
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view and compare information about the impact factors of similar journals. JCR calculates their similarity using a complicated relatedness (R) value. This takes into account: the total number of articles in the related journal, the total number of citations to and from the journals. A fuller explanation is given on the website. The Eigenfactor Score a relatively new measure developed by University of Washington biologist Carl T. Bergstrom which measures the number of times articles from the journal published in the past five years have been cited in the JCR year. Further details on this is provided in the section above and in the other sources section of this guide.
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Printing and saving results •
Create a marked list by ticking the boxes next to the results you retrieve. Then select the option
and choose to save the file or to format it for printing.
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You can save copies of the graphs and tables. Move your cursor over the image. Icons then appear to print, save or email the image usually in jpg format. The publisher website has a tutorial: http://scientific.thomsonreuters.com/training/jcr/#materials
ISI web of Knowledge Content • •
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ISI contains references to 1,000s of journal articles covering the social sciences and humanities. Sort your search results to see those hits which have been cited the most times. This can be regarded as a general indicator of the quality and impact of the article. However, you should remember that sometimes authors may cite an article in order to criticize or disagree with it. You can quickly locate information on the number of times a specific journal article has been cited Find out general information on the research output of a specific author. Set up alerts to be notified when an article is cited.
Access • • •
To access the database search for the title (ISI web of knowledge )on the LSE library catalogue Expand the catalogue record and click on the online access Field. Click on the title of the resource. Access using your LSE Network username and password. Once you have logged onto the main ISI database click on the yellow tab Select a database then choose Web of science
Searching Locating the most highly cited articles in your field • • •
Run your search. When the results list appears. Use the option sort by to order the hits by times cited. This will move the most highly cited articles to the top of the list. Under each reference is the number times cited. To view articles which have cited the one you are reading click on the number. You can conduct a statistical analysis of the citing articles. Click on Analyze Results To see barcharts on a number of facts about the citing articles. This includes where they were published (e.g. country), number of authors and their institutional affiliations)
Finding out who has cited a specific article • •
Search for the title of the article. Expand the full record. It usually appears in this format.
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Click on the cited by option to see the number and link through to the citing records. Remember that some may be criticising the original article! The Citation map option (middle of screen) gives you a graphical representation of the citing articles. This can be done from one generation (mapping those articles/authors that cited the original article) or to second generation. The latter is intended as a long term measure of the impact of the article it links to articles which cited the first generation articles. On the right hand side of the screen in the blue box some articles have the option (listed under additional information) to view the impact factor of the journal in which the article was published. This is a measure of how often on average articles from that journal are published. It can help you in deciding the relative importance of the article. You can also opt to be notified by email when the article is cited. Note this occurs when an article is cited in web of Science. It does not include citations elsewhere (such as on the general Internet).
Finding out information about how often individual authors have been cited. • •
The database mainly focuses upon the impact of journal titles, however some more limited information on the impact of individual authors can be obtained. Search for the author. Remember authors may use different versions of their name in different publications. Therefore a good tip is to truncate the first name to allow for all variations. E.g. for Christine Smith enter Smith, C*. From the results list choose the option refine you results (from the left hand side of the screen) and then select the institution/ institutions in which the individual has been based. For a full list of publications it may be necessary to gain information about the individual’s career.
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Once you have the authors list of publications, from the main search results screen choose the create citation report option from the right hand side of the screen. This presents graphs on the number of items published per year, number of citations per year, It is possible to remove the number of self –citations from the list Each entry gives the authors H-Index. This measure was developed by J.E. Hirsch and published in Proceedings of the National Academy of Sciences of the United States of America 102 (46): 16569-16572 November 15 2005. It is intended to measure both the productivity and impact of the published work of a 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 people's publications. Note each entry gives the number of average citations per year for the author. In order to be scientific one ought to compare this average with others working in the same field. One way of doing this very simply is to compare average citations for individual journal articles published in the same journal in the same year. . Search for the journal title and year of the articles to retrieve the full list then compare the citation counts. Enter a full record to call up the citation impact factor for the individual title. This gives the average number of citations.
SCOPUS
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SCOPUS contains references to 1,000s of journal articles covering the sciences, social sciences and humanities. It is a competitor to ISI and its results will differ. This is because it indexes a slightly different list of journals and uses some different methods of calculation. However, it is highly regarded. The Australian Research Council uses it for research evaluations. http://www.arc.gov.au/era/citation.htm Citation data is from 1996 onwards. This is a shorter time span than ISI. However, reviewers often feel that it indexes more non –English language titles then ISI and a broader range of titles from outside of Europe and North America. It is particularly well regarded for medical/ scientific analysis. For instance see this article Comparisons of Citations in Web of Science, Scopus, and Google Scholar for Articles Published in General Medical Journals Abhaya V. Kulkarni, MD, PhD; Brittany Aziz, BHSc; Iffat Shams, MPH; Jason W. Busse, DC, PhD , JAMA. 2009;302(10):1092-1096. http://jama.ama-assn.org/cgi/content/abstract/302/10/1092
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You can use SCOPUS to sort your search results to see those hits which have been cited the most times. This can be regarded as a general indicator of the quality and impact of the article. However, you should remember that sometimes authors may cite an article in order to criticize or disagree with it. You can quickly locate information on the number of times a specific journal article has been cited Find out citation information on the research output of a specific author. Locate citation information on research output from specific universities. Find data on journal titles – the number of articles they publish and how often these are cited. Set up alerts to be notified when specific articles, authors are cited
Access • •
To access the database search for the title (on the LSE library catalogue Expand the catalogue record and click on the online access Field. Click on the title of the resource. Access using your LSE Network username and password.
Searching Locating the most highly cited articles in your field • •
Run your search. When the results list appears. Click on the word Citations (highlighted in blue on the right of the screen) to order the hits by times cited. This will move the most highly cited articles to the top of the list. To view the citing articles click on the number in the citations column.
Finding information on specific journal titles. •
ISI Journal Citation reports provides an easier route for quickly generating rankings of the most highly cited journals in a specific subject area.
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However, it is possible to quickly compare up to 10 journals in terms of numbers of items published and numbers of citations (from 1995 onwards) From the main search screen search for the journal title using the Source Title field. This will retrieve a list of all the articles published on it. Click on the name of the journal in the source title column. Information on the number of citations to each article within it. Alternatively click on the Journal analyzer to view graphs on citation information for all issues of the journal (since 1995) This displays in the format.
The graph displays the total number of documents published in the journal in the year, the total number of citations in the year and the percentage of articles which were not cited. o One of the ranking used is SJR . This is A free journal ranking system developed by a research group from the University of Granada, Extremadura, Carlos III (Madrid) and Alcalá de Henares using Google page ranking technology. A full description is online at: http://www.scimagojr.com/SCImagoJournalRank.pdf o It Ranks the impact and number of citations in specific journals, number and impact of citation across over 200 different subject areas and from over 200 specific countries.Note this is a different ranking system to that used by ISI SNIP Source Normalised Impact per paper This aims to correct for differences in citation frequency in different fields. It is easy to compare the impact of up to 10 different titles. Simply search for the journal and once the results have been retrieved drag and drop the title into the Journals in the chart box on the right hand side of the screen. It is then possible to compare titles.
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Results can be exported by email or downloaded.
Finding out who has cited a specific article • •
Search for the title of the article. Expand the full record. It usually appears in this format.
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The number of times cited is displayed on the right of the screen. Click on the number to view all the citing articles. Note most citation information is from 1996 onwards. More historic data can be traced on ISI web of Knowledge. Use the set alert option to receive an email when an article in SCOPUS cites this title. This means that it may give slightly different results than those retrieved from setting up an alert from ISI. Note to use this service you will need to register for a free personal account on the site.
Finding information on specific authors •
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Choose the author search option. Enter surname and intitials or first name. It is usually better to enter only the initial of the author as sometimes they may not cite their full name in publications. It is also possible to enter the affiliation (university) of the author. Scopus will show variations of names in the results list. It is easy to combine these by simply marking the boxes next to the names.
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From the results screen you can opt to view the individual documents or view the citation overview. The citation overview gives information on the output and impact of the author. Typical results look like this.
The overview options enable you to select a different range of citations and to exclude self citations The total number of documents written by the author is displayed on the left. In this example there are 59. Details about each of the documents is listed in the table below. The columns give the number of times each one has been cited on a specific year. Click on the number to go to the citing documents. The total overall number of citations for this author (from all his/her papers) are displayed at the top of the table. The results can also be displayed as an h-Graph This measure was developed by J.E. Hirsch and published in Proceedings of the National Academy of Sciences of the United States of America 102 (46): 16569-16572 November 15 2005. It is intended to measure both the productivity and impact of the published work of a 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 people's publications.
Finding information on specific organizations
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It is possible to quickly generate some data on the number and citation of articles from authors affiliated to a specific university From the main search screen choose Affiliation search. Enter the name of the institution. Note enter London School of Economics not LSE Scopus will give a list of institutions which match your search. Under each record is the option (highlighted in blue) to find unmatched affiliations. Choose this to look for alternative misspellings of the institution name or slightly different variations. If you find any relevant hits from the unmatched affiliations list tick the box next to the title to quickly group them with the main affiliation. A typical affiliation results page looks like this.
It is possible to view the total number of documents published in a specific time period . Note this is usually 2005 onwards. Click on the number to link through to the documents. To get data on the number of citations go to the documents list. Check all documents and then view the citation overview Browse the source list to view a list of the journals in which the articles were published. Affiliating institutions lists those which were listed as collaborators on published articles. This may not therefore be exhaustive. Choose the documents alert to receive an email or RSS feeds when new articles are published by the institution.
• Other sources of Journal citation data Unfortunately the process of generating journal citation data is not without controversy. For a useful introduction see: Michael Norris, Charles Oppenheim. Comparing alternatives to the Web of Science for coverage of the social sciences’ literature. Journal of Informetrics. Available online at: http://info.scopus.com/researchtrends/archive/RT4/exp_op.htm A recent report by the Research Information Network. The UK's share of world research output http://www.rin.ac.uk/our-work/communicating-and-disseminating-research/uk-share-worldresearch-outputs-investigation also highlighted how different research reports can get different results depending on the biometrics they use. This means that while the JCR is highly recommended other sources may be available One new method is the Eigenfactor.
Eigenfactor Content •
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Developed by University of Washington biologist Carl T. Bergstrom. This metric, which is calculated by using network theory, ranks journals according to influence. An article on its approach can be read at http://pubs.acs.org/cen/science/86/8621sci1.html. In addition to citation it takes into account the amount of time users spend reading the journal and its data is taken from JCR titles but used in different ways. Details at http://www.eigenfactor.org/faq.htm Eigenfactor appears as a category on JCR search results but more details on its methods, associated technical papers appear on the home website.JCR contains results from 2007 onwards There is also an option to conduct a cost effectiveness search which ranks journals by broad subject area according to the value-per-dollar that they provide.
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http://www.eigenfactor.org/ JCR search results also have a field for Eigenfactor results.
Interpreting results. It is possible to search by journal title or discipline. Main emphasis is upon scientific titles. A typical search result looks like this.
Article Influence score measures the average influence, per article, of the papers in a journal. As such, it is comparable to Thomson Scientific's widely-used Impact Factor. Article Influence scores are normalized so that the mean article in the entire Thomson Journal Citation Reports (JCR) database has an article influence of 1.00. For example In 2006, the top journal by Article Influence score was Annual Reviews of Immunology, with an article influence of 27.454. This means that the average article in that journal has twenty seven times the influence of the mean journal in the JCR. • •
Scopus is not currently available in the LSE Library. However, it is offered in the British Library reading Rooms http://www.bl.uk/ at St Pancras. Also there is a free version called SCImago (further information below )
A free source which is becoming increasingly well known is The SCImago Journal & Country Rank.
SCImago Journal & Country Rank Content •
A free journal ranking system developed by a research group from the University of Granada, Extremadura, Carlos III (Madrid) and Alcalá de Henares using Google page ranking technology. A full description is online at: http://www.scimagojr.com/SCImagoJournalRank.pdf
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Ranks the impact and number of citations in specific journals, number and impact of citation across over 200 different subject areas and from over 200 specific countries. Data is taken from the Scopus database and dates from 1996 onwards. Therefore if a title is not indexed in Scopus information will not be available Wide subject coverage. Including medical subjects, business, economics. More emphasis upon the Sciences than JCR. Site enables maps and charts comparing rankings to be generated by the user.
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Free access at http://www.scimagojr.com/
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Access
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Each search generates a number of ranking criteria. These are Journals can be ranked by: SJR, Cites per document (2 years), H Index, Title, Total documents, Citable documents (3 years), and Total cites (3 years). SJR (SCImago Journal Rank). This is a complicated indicator which is supposed to express the prestige of the title. It is generated according to the number of connections that a journal receives through the number of citations of its documents in SCOPUS divided between the total of documents published in the year, weighted according to the amount of incoming and outgoing connections of the sources. This is explained more fully at: http://www.scimagojr.com/SCImagoJournalRank.pdf H Index: an index (originally suggested by Jorge E. Hirsch, as a tool for determining theoretical physicists’ relative quality) that is widely used in the sciences. It expresses the scientific productivity and the scientific impact of a journal in the SCOPUS database. It is based on the set of the journal’s most quoted papers and the number of citations that they have received in others publications. For more information see: http://www.cs.ucla.edu/~palsberg/h-number.html Total Docs./Total Documents: The total number of items published during the selected period. Total Docs. (3years): Total of documents published in a 3 year period. The calculation of this indicator takes into account the total of works (any type of document) published in the three previous years. For example, Total Docs (3years) of 2006 is calculated on the basis of the works published in 2003, 2004 and 2005. Total Cites (3years)/Total Cites: Total of document citations received by a journal in a 3 year period. This indicator is estimated taking account of all types of documents contained in a journal in the selected year and the bibliographical references they include to any published document in the three previous years. Citable Docs./Citable Documents: Total of articles and reviews published in a 3 year period. Ref. x Doc.: Average of references by document. In order to find this indicator the total of references included in the documents contained in a journal for the selected year is divided by the total of documents published in that same year. Country: Journal’s country. Self Cites: Journal self-citation. This indicator is estimated taking account of all types of documents contained in a journal in the selected year citing the journal in which they are published. Non-citable documents. This indicator is calculated by the difference between Total Docs. And Citable Docs. Cited Documents (Cited Doc.): Number of documents that received at least one citation in a 3 year period. Uncited Documents (Uncited Doc.): Number of documents that did not receive at least one citation in a 3 year period.
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Documents with authors from several countries: Number of documents published by authors from several countries.
ISI Highly cited com Content • • • • •
Maintained by Thomson Scientific publishers ISI web of Science. Aims to offer a ‘Gateway to the most highly influential scientists and scholars worldwide Provides information on 250 of the most important scientists worldwide. Using 21 categories (mainly scientific) Individuals are selected using analysis of the most highly cited papers from over 20 years data taken from the ISI Web of science databases. Individual entries include dates of birth, key posts held in career, major research wards and projects, lists of publications (indexed in the ISI databases). It also links through to articles taken from the SCiencewatch website (which is described below).
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http://isihighlycited.com/ is the free version It is also an option on the main Web of Science website. Find it listed under the other Databases option. The latter offers links through to the author’s publications (where the LSE has a subscription to the full text of the title).
ScienceWatch.Com – trends in research Content A service offered by Thomson Reuters which offers free access to articles and ranking taken from their Essential Science Indicators and other databases. It therefore tends to emphasize trends in scientific subjects. It includes interviews, articles and a Scibytes section with rankings of hop topic areas and most highly cited papers. Access http://sciencewatch.com/ Citation Impact center http://science.thomsonreuters.com/citationimpactcenter/ Site maintained by Thomson Reuters has blogs and news relating to citations mainly referenced from their products which include the ISI Journal Citation reports.
Further help • • •
Consult the Library web pages to book a course http://www2.lse.ac.uk/library/training/Home.aspx Ask at the help desk, Library First Floor Email the library for help http://www2.lse.ac.uk/library/enquiriesandfeedback/Home.aspx
Last Edited 11/2010 HD