The h-index, h-core citation rate and the bibliometric profile of the Scopus database
Purpose The h-index has been used to evaluate research productivity and impact (as manifested by the number of publications and the number of citations received) at many levels of aggregations for various targets. The purpose of this paper is to examine the bibliometric characteristics of the largest multidisciplinary databases that are the most widely used for measuring research productivity and impact. Design/methodology/approach - The paper presents preliminary findings about the Scopus database. It is to be complemented and contrasted by the bibliometric profile of the Web of Science (WoS) database. Findings - The test results showed that 18.7 million Scopus records had one or more cited references, representing 42 per cent of the entire database content. The ratio of cited reference enhanced records kept slightly increasing year by year from 1996 to 2009. Scopus classifies the journals and other serial sources into 27 broad subject areas by assigning its journals to 21 science disciplines, four social science disciplines, a single Arts and Humanities category, and/or a multidisciplinary category. The distribution of records among the broad subject areas can be searched in Scopus using the four-character codes of the subject areas. A journal or a single primary document may be assigned to more than one subject area. However, Scopus overdoes this, and it significantly distorts the h-index for the broad subject areas. The h-index of the pre-1996 subset of records for the 21,066,019 documents published before 1996 is 1,451, i.e. there are records for 1,451 documents in that subset that were cited more than 1,450 times. The total number of citations received by these 1,451 papers (i.e. the h-core, representing the number of items that contribute to the h-index) is 4,416,488, producing an average citation rate of 3,044 citations per item in the h-core of the pre-1996 subset of the entire Scopus database. For the subset providing records for 23,455,354 documents published after 1995, the h-index is 1,339, so the total number of citations must be at least 1,792,921. In reality the total number of citations received by these papers is 3,903,157, yielding a citation rate of 2,915 citations per document in the h-core. For the entire Scopus database of 44.5 million records the h-index is 1,757. Originality/value - Knowing the bibliometric features of databases, their own h-index and related metrics versus those of the alternative tools can be very useful for computing a variety of research performance indicators. However, we need to learn much more about our tools in our rush to metricise everything before we can rest assured that our gauges gauge correctly or at least with transparent limitations. Learning the bibliometric profile of the tools used to measure the research performance of researchers, departments, universities and journals can help in making better informed decisions, and discovering the limitations of the measuring tools.
serials very large databases research work