Coverage analysis of Scopus: A metric approach

ed/Indexed Universe 12,597 73,708 17.09% 61,111 Core 11,273 41,049 27.48% 29,756 Electronic Journal Universe 10,189 56,215 18.13% 46,026 Core 9,535 29,309 32.53% 19,774 Magazines for Libraries Universe 2,712 11,646 23.29% 8,934 Core 2,601 7,458 34.88% 4,857 F. DE MOYA-ANEGÓN et al.: Coverage analysis of Scopus Scientometrics 73 (2007) 57 Scopus matches 5.55% of the journal titles in relation to Ulrich’s Universe version. These represent, in turn, 6.59% of titles that match and of those being analysed; 32.51% of these are peer-reviewed, 17.09% are indexed in databases, and 18.13% are electronic journals. In relation to the Core version, Scopus represents 18.94% of the Ulrich collection and comparisons are carried out starting from 20.40% of the matching journals. Out of this percentage, 32.51% are peer-reviewed, 27.48% are available on data bases, 32.53% are electronic journals. Altogether, 62.22% are listed in the JCR. These are the values that will be used to establish the threshold; the variables studied will be evaluated as above or below this average value, that is, over or under-represented. Subject distribution As a result of the matching process with the Scopus collection, subject distribution in Ulrich’s Core was seen to divide knowledge into 151 categories, while Scopus has titles in 120 of them. This means that its subject coverage compared to the worldwide point of reference is 79.47%, taking into account the 2,820 titles made reference to above (Table 1). Figure 1 shows the subject distribution of the two journal collections from a dual perspective. Figure 1. Journal distribution by subject areas – Ulrich’s Core F. DE MOYA-ANEGÓN et al.: Coverage analysis of Scopus 58 Scientometrics 73 (2007) To the left, the percentual distribution is shown, with only the categories that contain at least 10 journals (representing 98.43% of the collection) included. The columns show the number of titles in each category in Scopus in descending order, while the points show the Ulrich Core corresponding values. To the right, the overall distribution between the two collections is shown taking all the categories into account (including those with less than 10 journals) and indicating which are furthest away from the average (above or below the line of regression). The squared R value reflects the similarity of the distribution on the whole. In Ulrich’s Core, 47.5% of all the categories also represented in Scopus pertain to Medicine, Basic Sciences and Technology. These account for 77.46% of the total journals. In turn, 34.17% of the categories belong to Social Sciences, with 19.39% of the collection’s journals, and the rest are from Humanities. As can be seen, the categories showing disparity are mainly in Social Sciences and Humanities. This is shown in Jacso’s work (Figure 2) and in the information provided by Scopus on its website. In Table 3 (and the following), categories with at least ten titles are shown, with 5 columns of the percentage distribution in relation to Ulrich’s Core. They provide information on the Scopus collection (% S/SC); the Ulrich collection (% U/UC); the percentage of Scopus titles in relation to Ulrich in descending order (%S/UC); and the Scopus refereed journals in relation to Ulrich (Ref/UC). To assess the balance of international coverage, and bearing in mind that the percentage of Scopus journals in relation to Ulrich Core is 20.40%, this value can be adopted as the threshold point of average representation (hence, categories with higher values are the best represented). As seen in Table 3, 52% are over-represented in terms of coverage and 62% are above the threshold of the peer-reviewed variable. For the total categories with journals, 44% are over-represented. Most of these are from the sciences (81.13%), and 54% have a higher percentage than the average for refereed journals (32.51%) of the whole collection. The determination coefficient in this case is 0.68 and the Pearson coefficient is 0.81. In order to find the degree of similarity, we applied the Pearson correlation coefficient and obtained a value of 0.9. This reflects the fact that in various categories there are many more journals than in Scopus, as illustrated in Figure 1. By isolating these cases, we see they are mostly from the Humanities and the Social Sciences (probably non-academic). In terms of the determination coefficient, Figure 1 is very illustrative: we can say that Scopus generally has quite a homogenous global representation in all areas except Arts and Humanities. This has been pointed out in previous studies (DEIS & GOODMAN, 2004) and can be seen on Scopus’s own website, where it describes its subject coverage. F. DE MOYA-ANEGÓN et al.: Coverage analysis of Scopus Scientometrics 73 (2007) 59 Table 3. Subject ranking according to the percentage of Scopus journals in Ulrich’s Core Abr. Ulrich’s subject %Scopus % Ulrich %S/U % Ref S/U PLAS Plastics 0.23 0.09 45.61 52.78 PETR Petroleum and gas 0.40 0.17 43.81 55.56 TIF Textile industries and fabrics 0.21 0.09 42.11 53.85 PHAR Pharmacy and pharmacology 2.26 1.07 40.09 50.00 MET Metallurgy 0.82 0.40 39.17 48.84 CHE Chemistry 3.74 1.83 38.86 48.20 ELE Electronics 0.49 0.24 38.10 44.44 ENG Engineering 5.40 2.77 37.06 50.41 DAA Drug abuse and alcoholism 0.32 0.16 37.00 50.75 VET Veterinary science 0.84 0.44 36.47 49.73 PHY Physics 3.33 1.83 34.56 45.62 PHS Public health and safety 0.69 0.38 34.20 45.83 MED Medical sciences 26.37 14.70 34.08 44.77 GERON Gerontology and geriatrics 0.53 0.30 33.70 48.25 BIOL Biology 10.90 6.45 32.11 42.92 COMP Computers 3.44 2.07 31.66 40.40 INS Instruments 0.10 0.06 31.43 47.62 PSY Psychology 3.35 2.04 31.18 43.47 PAL Paleontology 0.31 0.19 31.03 51.56 STA Statistics 0.34 0.21 30.95 50.68 NUT Nutrition and dietetics 0.53 0.33 30.20 40.74 ENE Energy 0.69 0.44 29.70 46.46 ENV Environmental studies 2.02 1.29 29.64 44.47 WR Water resources 0.29 0.19 29.31 49.15 FOOD Food and food industries 0.36 0.24 29.17 44.19 MMI Mines and mining industry 0.29 0.20 28.57 40.00 ES Earth sciences 2.99 2.04 27.89 41.55 GEO Geography 1.15 0.79 27.82 42.13 MATH Mathematics 3.24 2.25 27.40 37.02 CGP Ceramics, glass and pottery 0.14 0.10 26.23 48.28 HOU Housing and urban planning 0.37 0.27 26.06 43.68 AM Alternative medicine 0.20 0.15 25.84 26.92 OHS Occupational health and safety 0.22 0.16 25.00 40.74 AERO Aeronautics and space flight 0.38 0.30 23.91 39.19 METE Meteorology 0.29 0.24 23.61 39.47 FF Forests and forestry 0.43 0.37 22.32 41.00 FF Fish and fisheries 0.24 0.21 21.54 37.50 TRAN Transportation 0.50 0.50 19.21 36.07 HAN Handicapped 0.14 0.14 19.05 32.50 HFA Health facilities and administration 0.17 0.17 18.87 34.00 CRIM Criminology and law enforcement 0.33 0.34 18.63 33.71 BUI Building and construction 0.17 0.18 18.35 40.91 SSWE Social services and welfare 0.52 0.54 18.24 29.41 BE Business and economics 4.65 5.13 17.20 28.36 PS Population studies 0.22 0.24 17.01 36.84 ASTRO Astronomy 0.29 0.33 16.92 36.56 AGRI Agriculture 1.50 1.70 16.80 32.83 SOC Sociology 1.11 1.26 16.80 30.63 F. DE MOYA-ANEGÓN et al.: Coverage analysis of Scopus 60 Scientometrics 73 (2007) Table 3. (cont.) Abr. Ulrich’s subject %Scopus % Ulrich %S/U % Ref S/U TCW Technology: comprehensive works 0.28 0.35 15.09 23.60 CYABOUT Children and youth_about 0.19 0.27 13.33 26.56 LIS Library and information sciences 0.64 0.96 12.67 24.81 PFH Physical fitness and hygiene 0.12 0.19 12.39 25.64 GH Gardening and horticulture 0.11 0.18 12.04 28.89 POL Political science 1.41 2.26 11.85 25.96 SCW Sciences: comprehensive works 1.19 1.96 11.51 22.96 CONS Conservation 0.16 0.28 11.24 32.73 WS Women's studies 0.13 0.26 9.49 17.28 EDU Education 1.95 3.95 9.38 18.96 PA Public administration 0.16 0.34 9.22 17.89 ANTH Anthropology 0.42 0.86 9.18 18.75 SSCW Social sciences: comprehensive works 0.61 1.38 8.36 18.48 LAW Law 1.09 3.24 6.41 17.12 MIL Military 0.10 0.29 6.18 6.90 LING Linguistics 0.78 2.70 5.48 12.70 TT Travel and tourism 0.09 0.33 5.03 28.13 ARTT Architecture 0.09 0.36 4.59 11.59 EI Ethnic interests 0.10 0.44 4.07 8.51 PHIL Philosophy 0.26 1.46 3.39 6.67 ARCH Archaeology 0.17 1.33 2.48 8.11 HIS History 0.40 4.48 1.69 4.61