Thomson Reuters

The Thomson Scientific Journal Selection Process

Thomson Scientific is committed to providing comprehensive coverage of the world's most important and influential journals to meet its subscribers' current awareness and retrospective information retrieval needs. Today Web of Science covers over 9,000 international and regional journals and book series in every area of the natural sciences, social sciences, and arts and humanities.

But comprehensive does not necessarily mean all-inclusive. 1

Why Be Selective?*

It would appear that, in order to be comprehensive, an index to scientific journal literature might be expected to cover all the scientific journals published. This approach would be not only impractical economically, but as analyses of the scientific literature have shown, unnecessary. It has been demonstrated that a relatively small number of journals publish the bulk of significant scientific results. This principle is often referred to as Bradford's Law. 2

In the mid-1930's S. C. Bradford realized that the core literature for any given scientific discipline was composed of fewer than 1,000 journals. Of these 1,000 journals, there are relatively few with a very strong relevance to the given topic, whereas there are many with a weaker relevance to it. Those with a weak relevance to the given discipline or topic, however, typically have a strong relevance to some other discipline. Thus, the core scientific literature can form itself around various topics, with individual journals becoming more or less relevant depending on the topic. Bradford understood that an essential core of journals forms the literature basis for all disciplines, and that most of the important papers are published in relatively few journals.3

* In order to evaluate a journal for possible coverage we must receive at minimum three consecutive current issues, one at a time as they are published, and/or free electronic access to the publication. Send print issues to Publication Processing, 3501 Market Street, Philadelphia, PA 19104, USA.)

More recently, an analysis of 7,528 journals covered in the 2005 JCR® revealed that as few as 300 journals account for more than 50% of what is cited and more than 25% of what is published in them. A core of 3,000 of these journals accounts for about 75% of published articles and over 90% of cited articles. Furthermore, this core is not static. Its basic composition changes constantly reflecting the evolution of scholarly topics. Our mission is to update journal coverage in Web of Science by identifying and evaluating promising new journals, and deleting journals that have become less useful.

The Evaluation Process

Journal evaluation and selection is ongoing at Thomson Scientific with journals added to and deleted from the database as frequently as every two weeks. Each year, Thomson Scientific's editorial staff reviews over 2,000 journal titles, and selects around 10-12% of the journals evaluated for inclusion in the Thomson Scientific database. Moreover, existing journal coverage in Thomson Scientific products is constantly under review. Journals now covered are monitored to ensure that they are maintaining high standards and a clear relevance to the products in which they are covered. The journal selection process described here is applied to all journals in Web of Science®, whether covered in Science Citation Index Expanded™, Social Sciences Citation Index®, or Arts & Humanities Citation Index®. Some special consideration is given in the evaluation of social science and arts & humanities journals, particularly with regard to citation analysis. These considerations are noted below.

Many factors are taken into account when evaluating journals for coverage, ranging from the qualitative to the quantitative. The journal's basic publishing standards, its editorial content, the international diversity of its authorship, and the citation data associated with it are all considered. No one factor is considered in isolation, but by combining and interrelating the data, the editor is able to determine the journal's overall strengths and weaknesses.

The Thomson Scientific editors performing journal evaluations have educational backgrounds relevant to their areas of responsibility as well as experience and education in information science.

Basic Journal Standards

Timeliness of publication is a basic criterion in the evaluation process. It is of primary importance. A journal must be publishing according to its stated frequency to be considered for initial inclusion in the Thomson Scientific database. The ability to publish on time implies a healthy backlog of manuscripts essential for ongoing viability. It is not acceptable for a journal to appear chronically late, weeks or months after its cover date.5 To measure timeliness we need to see three consecutive current issues, one after another, as soon as they are published.

Timeliness is also essential for electronic journals. If the e-journal is publishing distinct issues at a stated frequency, these issues should appear online in a timely manner.

However, when an e-journal publishes articles one at a time rather than collecting articles for release as an 'issue' we take a slightly different approach to measuring timeliness. In these cases the editors look for a steady flow of articles over several months time.

Thomson Scientific also notes whether or not the journal follows international editorial conventions, which optimize retrievability of source articles. These conventions include informative journal titles, fully descriptive article titles and abstracts, complete bibliographic information for all cited references, and full address information for every author.

English is the universal language of science at this time in history. It is for this reason that Thomson Scientific focuses on journals that publish full text in English or at very least, their bibliographic information in English. There are many journals covered in Web of Science that publish only their bibliographic information in English with full text in another language. However, going forward, it is clear that the journals most important to the international research community will publish full text in English. This is especially true in the natural sciences. In addition, all journals must have cited references in the Roman alphabet.

Application of the peer review process is another indication of journal standards and indicates overall quality of the research presented and the completeness of cited references.6 It is also recommended that, whenever possible, each article publish information on the funding source supporting the research presented.

Editorial Content

As mentioned above, an essential core of scientific literature forms the basis for all scholarly disciplines. However, this core is not static--scientific research continues to give rise to specialized fields of studies, and new journals emerge as published research on new topics achieves critical mass. Thomson Scientific editors determine if the content of a journal under evaluation will enrich the database or if the topic is already adequately addressed in existing coverage.

With an enormous amount of citation data readily available to them, and their daily observation of virtually every new scholarly journal published, Thomson Scientific editors are well positioned to spot emerging topics and active fields in the literature.

International Diversity

Thomson Scientific editors look for International Diversity among the contributing authors and the journal’s editors and Editorial Advisory Board members. This is particularly important in journals targeting an international audience. Today’s scientific research takes place in a global context and an internationally diverse journal is more likely to have importance in the international community of researchers.

As the global distribution of Web of Science expands into virtually every region on earth, the importance of regional scholarship to our emerging regional user community also grows. Selection criteria for regional journals are the same as for international journals although citation analyses play a somewhat different role in the outcome. For example, the importance of the regional journal would be measured more in terms of the specificity of its content. Will it enrich our coverage of a particular subject or provide studies with a specific regional perspective?

Many excellent regional journals target a local rather than an international audience. Therefore, the emphasis on extensive international diversity is less than for internationally focused journals.

All regional journals selected must be publishing on time, have English-language bibliographic information (title, abstract, keywords), and be peer reviewed. Cited references must be in the Roman alphabet.

Citation Analysis

The Thomson Scientific evaluation process is unique in that Thomson Scientific editors have a wealth of citation data available to them. The importance of interpreting and understanding these data correctly cannot be emphasized too strongly. Using quantitative citation data to measure impact is meaningful only in the context of journals in the same general discipline. For example, smaller fields like crystallography do not generate as many articles or citations as do larger fields such as biotechnology or genetics. Likewise, in some areas, particularly in the arts and humanities, it may take a relatively long time for an article to attract a meaningful number of citations. But in other areas, such as the life sciences, it is not unusual for citations to accrue rapidly and peak after two or three years.7 These facts must be taken into consideration if citation data are to be used correctly.

Citation analyses takes place on at least two levels. We look for citations to the journal itself, as expressed by Impact Factor and/or total citations received. We also examine the citation record of the contributing authors, a useful study in evaluating new journals where a citation history at the journal level does not yet exist.

Likewise, established journals that are not covered are often re-evaluated. These journals can experience new growth in citation impact resulting from changes such as translation into English, change in editorial focus, change in Publisher, medium, etc.

Because Thomson Scientific captures all cited references from each of the 9,300 journals covered, citation information is available on journals not covered as well as those that are covered.

Self-citation rates are also taken into consideration. The self-cited rate relates a journal’s self-citations to the number of times it is cited by all journals, including itself. For example, journal X was cited 15,000 times by all journals, including the 2,000 times it cited itself. Its self-cited rate is 2/15 or 13.3%.

A high volume of self-citation is not unusual or unwarranted in journals that are leaders in a field because of the consistently high quality of the papers they publish, and/or because of the uniqueness or novelty of their subject matter. Ideally, authors reference the prior publications that are most relevant to their current results, independently of the source journal in which the work was published. However, there are journals where the observed rate of self-citation is a dominant influence in the total level of citation. For these journals, self-citation has the potential to distort the true role of the title as a participant in the literature of its subject. 8

Eighty per cent of all journals listed in the JCR Science Edition have self-citation rates less than or equal to 20%. This shows that self citation is quite normal for most journals and is expected. Significant deviation from this normal rate, however, prompts an examination by Thomson Scientific to determine if excessive self-citations are being used to artificially inflate the Impact Factor. If we determine that self-citations are being used improperly, the journal’s Impact Factor will not be published and the journal may be considered for deselection from the Web of Science.

Social Sciences

All social science journals undergo the same thorough evaluation as journals in the natural sciences. Publishing standards, editorial content, international diversity, and citation data are all considered. Standard citation metrics are analyzed while keeping in mind that overall citation rates in the social sciences are generally lower than those in the natural sciences.

Regional studies have special importance in the social sciences as topics of local rather than global interest are often the subject of scholarly research.

Arts & Humanities

Publishing standards, including timeliness, are important in the evaluation of arts and humanities journals. Citations patterns in the arts and humanities, however, do not necessarily follow the same predictable pattern as citations to social sciences and natural sciences articles. In addition, arts and humanities journal articles frequently reference non-journal sources (e.g., books, musical compositions, works of art and literature). English-language text is not a requirement in some areas of A&H scholarship where the national focus of the study precludes the need for it; for example, research in regional literatures.

Electronic Journals

As stated earlier, the basic mission of Thomson Scientific is to provide access to the world's most important and influential journals regardless of the media in which they are published.

Publishing Standards, Editorial Content, International Diversity, and Citation Analysis are all considered when evaluating a purely electronic journal.

Evaluating the timeliness of publication of an e-journal may require a somewhat different approach. If the e-journal is publishing distinct issues the Thomson Scientific editor looks for the appearance of these in a timely manner. However, when an e-journal publishes articles one at a time rather than collecting articles for release as an 'issue' the editor simply looks for a steady flow of articles over several months time.

The Format of Electronic Journals is extremely important to Thomson Scientific. Following are a set of guidelines for Electronic Journal formats. Following these guidelines helps insure correct citation of articles and reduces the possibility of ambiguity in citation of articles.

Insure that it is easy to identify the following elements:

• Journal Title
• Year of publication
• Volume and/or Issue Number (if applicable)
• Article Title
• Page Number or Article Number (one or the other is required; article number should not be the DOI) If your journal has page numbers and article numbers, list them separately and not merged
• together. EXAMPLE: Art. #23, pp. 6-10 and not 23.6-23.10
• Authors names and addresses
• Label all article identifiers such as DOIs, PIIs and Article Numbers
• A complete table-of-contents for each issue that includes the page/article number for each article (unless journal is being published as single articles)

Labeling these identifiers in both source articles and in citations helps insure their proper use by those referencing the article and correct labeling by abstracting and indexing firms such as Thomson Scientific.

• Each article must be assigned a unique page number or article number (whichever numbering scheme is being used) within any one given issue. Additionally, article numbers must be unique within an entire volume number. If the same article numbers are repeated in each issue within a volume, ambiguities will result when citing the original article. A citation to V 20, art. 1, May 2002, (even when adding the author's name), would be difficult to find if V 20, art. 1 June 2002 also exists. Avoid duplication of article numbers. References to Your Electronic Journal. Instruct authors to include the following information when citing your e-journal:
  • Journal title (use one standard abbreviation for your journal; avoid acronyms that may be confused with other titles)
  • Volume number (if applicable)
  • Issue Number (if applicable; within parenthesis)
  • Page number and/or article number (clearly identifying the article number as such)
  • Year of publication

How to Recommend Journals or submit a journal for evaluation

Thomson Scientific welcomes suggestions and recommendations for coverage. If you would like to recommend a journal for evaluation, please follow the links below and provide all necessary information as well as access to your journal either electronically or in print.

Recommend a journal for coverage in Web of Science at http://scientific.thomsonreuters.com/forms/isi/journalrec/.

Submit a journal for evaluation for Web of Science at http://scientific.thomsonreuters.com/forms/isi/journalsubmission/.

This essay was prepared by James Testa, Senior Director, Editorial Development & Publisher Relations, Thomson. Special thanks to Editorial Development staff members Katherine Junkins , Maureen Handel, Mariana Boletta, Ryan Joyce, Kathleen Michael, Rodney Chonka, Chang Liu, and Luisa Rojo for their critical reading and comments. .

1. Garfield, E., How ISI Selects Journals for Coverage: Quantitative and Qualitative Considerations. Current Contents, May 28, 1990.
2. Garfield, E., Citation Indexing (New York: John Wiley & Sons, 1979)
3. Ibid.
4. Garfield, E., The Significant Scientific Literature Appears in a Small Core of Journals. The Scientist V10 (17), Sept. 2, 1996.
5. Garfield, E., How ISI Selects Journals for Coverage: Quantitative and Qualitative Considerations. Current Contents, May 28, 1990.
6. Ibid.
7. Ibid.
8. McVeigh, M., Journal Self- Citation in the Journal Citation Reports – Science Edition. 2002. http://thomsonreuters.com/business_units/scientific/free/essays/selfcitation2002/.