Towards a comprehensive citation index for the Arts & Humanities
The Humanities is a hugely diverse field with output published in many regional and national journals, but also in book chapters and monographs (1). In their recent publication on comprehensive coverage of the Social Sciences and Humanities, Sivertsen and Larsen pointed out that: “A well-designed and comprehensive citation index for the Social Sciences and Humanities has many potential uses, but has yet to be realized” (2). In 2008–09 the European Science Foundation (ESF) created the European Reference Index for the Humanities (ERIH). “The reference index was created and developed by European researchers both for their own purposes and in order to present their ongoing research achievements systematically to the rest of the world” (3). As a result of the second round of the ERIH project and following revisions of the initial list, in 2011 the ERIH Revised Lists was published (4). Project MUSE is a not-for-profit full text platform of many Arts & Humanities journals with international relevance from primarily US based University Presses (5). In addition, local databases with comprehensive coverage of Social Science and Humanities journal articles exist, for example, in Flanders and in Norway (6). Multidisciplinary citation indexes like Scopus are fairly comprehensive in the Science, Technology and Medicine (STM) subject fields. However, it has remained a challenge to create an index that is comprehensive in both STM and Humanities.
Coverage of Humanities journals in Scopus
In 2008, Scopus covered around 2,000 Humanities titles. To further increase the number of Humanities titles in the database, project MUSE and the initial ERIH list were used to identify additional relevant titles in 2009. In 2011, a similar project was executed in which the coverage of the revised ERIH list, the Social Science Citation Index, the Arts & Humanities Citation Index, the titles list of Evaluation Agency for Research and Evaluation, France (AERES), and the Humanities journal indexes Cairns and Francis were used. These journals were reviewed and added to the database, together with the Humanities titles selected for Scopus coverage via the Scopus Title Evaluation Process (STEP). The Scopus coverage has now grown to almost 3,500 Humanities titles (and to 4,200 when also including Humanities-related titles) and includes all serial publication types, such as journals, book series and conference series.
That the origin of Humanities journals is diverse is shown by the vast number of publishers from which the journals are sourced. Also, in Humanities, there is less concentration of journals at a minority of publishers than for STM titles (see Figure 1). The diagonal represents a situation where each publisher contributes the same percentage of journals. The surface between the curve and diagonal is proportional to the Gini index, which is a measure for concentration. For STM the surface is larger than for Humanities, which means a higher Gini Index value and a stronger degree of concentration of journals amongst publishers.
Figure 1 – Cumulative percentage of journals versus cumulative percentage of publishers for STM and Humanities journals covered in Scopus (November 2012). Source: Scopus
In Scopus, the location of a journal is determined by the country in which the publisher is located. Most of the larger publishers are located in Western-Europe or North America; therefore most of the Humanities titles come from these regions. However, the Humanities content is published in 63 different countries. In the top 25 countries, there are six Eastern-European countries; three Scandinavian countries; two South-American countries; one African country and one Asian country (see Figure 2a). Looking at the regional diversity it is clear that Europe as a whole is best represented and Central & South America and Asia Pacific are underrepresented with respect to Humanities content (See Figure 2b).
Figure 2a (left): The number of Humanities titles covered in Scopus for the top 25 countries with most Humanities titles covered (November 2012). Figure 2b (right): Regional distribution of the number of Humanities titles covered in Scopus per region (November 2012). Source: Scopus
Since the majority of titles come from Anglo-Saxon countries it is to be expected that most titles have English as their primary publication language. However, 975 of the Humanities titles do not have English as their primary language and a further 500 English language titles have a second publication language. In total 32 different languages are covered. French, Spanish, German and Italian are the most occurring languages after English (see Figure 3). Most of the other frequently occurring languages are other European languages, with the notable exceptions of Russian and Turkish. More analysis about the publication language of Humanities content is provided in another article in this Research Trends issue (7).
Figure 3 – Proportion of non-English languages in Humanities journals in Scopus. Only languages with at least 10 titles are mentioned (November 2012). Source: Scopus
With respect to the subject classification of the Humanities titles, there is a fairly even distribution over the different sub-fields (see Figure 4).*) History is the largest field with more than 900 titles, after that Literature & Literary Theory (668), Language & Linguistics (649), Philosophy (445), Visual Arts (392) and Religious Studies (356) are the largest sub-fields. Of the Humanities-related subject fields, Cultural Studies (678), Linguistics & Language (673) and Law (462) are the most frequently occurring.Scopus
*) Titles can be classified in more than one subject field.
Humanities articles in Scopus (2007–11)
As of November 2012, the total number of Arts & Humanities articles in the database is a little over 1 million, just over 2% of the total database. All document types that are within the Scopus coverage policy are included in the article counts. From 2007 to 2011 the number of articles has grown from 42 thousand to 76 thousand articles per year, which comes down to a compound annual growth rate (CAGR) of 16.2% (see Figure 5). Particularly since 2009 the year-on-year growth of Humanities articles has increased substantially (20.1%), which is in line with the increase of Humanities indexed titles in the database.
Figure 5 –The growth percentage (green line, top) and the number (blue bars, below) of Humanities articles covered in Scopus per year in 2007–11 (30 November 2012). Source: Scopus
The US and the UK are the countries with the most Humanities articles during 2007–11 (see Table 1). All of the countries in the top 10 experience a year-on-year growth of more than 30%. Most remarkable is Spain with a year–on-year growth rate of 50%; despite the fact that the CAGR of Humanities articles published in the Spanish language remained in line with the overall growth rate at 17%.
Table 1 – Number of Humanities articles published per year for the top 10 countries by article output in Humanities (30 November 2012). Source: Scopus
Humanities book content
As many publications in Arts & Humanities are not published in journals but in books, for comprehensive coverage of Humanities research output it is also important to cover books (1), (8). The Books Enhancement Program was set up to tackle this issue. It aims to index around 75,000 books in Scopus by the end of 2015. Although books in all subject areas will be covered, the focus will be on those subject fields where books matter most: Social Sciences and Arts & Humanities. The selection policy of books content will be on a publisher level, taking into account aspects like the reputation of the publisher, the composition of the books list and expected impact of the books. As part of the Books Enhancement Program, full bibliographic metadata will be indexed as well as abstracts (where available), author and affiliation information and cited references. By capturing author and affiliation data, it will be possible to attribute a book chapter or monograph to an author, create profiles and measure output. This is also of relevance for new initiatives to create user-generated author profiles such as the Open Researcher and Contributor ID (ORCID) (9). Covering more comprehensive Humanities output will make it easier for researchers to create their ORCID profiles. By making the cited references available and matching the citations to records in the database, it will also be possible to display citation counts and measure impact.
In conclusion, various actions have been taken in order to make Scopus more comprehensive with respect to Humanities content. The number of Humanities titles covered and articles published in the database has grown substantially. Particularly Humanities journal output from North America and Europe seems to be covered well. Next steps will be to increase coverage of Humanities journal content from Asia, which currently seems to be underrepresented in the database. Also of importance will be to extend the source types to books and capture the relevant Humanities output that is not published in journals but in books. A fully comprehensive citation index for both STM and Humanities may not be there yet, but we are getting closer.