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Rather than trying to summarize the performance of a researcher in a single number (e.g., the h-index), our profiles aim to give a more detailed picture based on a variety of bibliometric statistics. Our profiles also offer the possibility of drilling down from an aggregate level to bibliometric statistics at the level of individual publications. CWTS emphasizes that especially in the case of analyses at the level of individual researchers it is crucial to be aware of the limitations of bibliometric statistics. Bibliometric statistics are more useful in some disciplines (e.g., natural and life sciences) than in others (e.g., social sciences). Also, the smaller the number of publications based on which bibliometric statistics are calculated, the lower the accuracy and reliability of the statistics. More generally, we emphasize that bibliometric statistics capture the scientific performance of a researcher only in a partial manner. Many important aspects of a researcher’s scientific performance may not be reflected in bibliometric statistics.
Database
Our bibliometric researcher profiles are based on the CWTS in-house version of the Web of Science (WoS) database produced by Thomson Reuters (Science Citation Index Expanded, Social Sciences Citation Index, and Arts & Humanities Citation Index). Publications that are not indexed in this database, such as books, book chapters, conference proceedings publications, and publications in journals not covered by WoS, are not included in a researcher’s profile. Publications that appeared before 1980 also are not included. We further emphasize that citations received from non-WoS-indexed publications are not counted.
Reports
A bibliometric researcher profile consists of four reports: Citation Impact I, Citation Impact II, Collaboration, and Publications. We discuss each of these reports in turn.
Citation Impact I report
The Citation Impact I report provides statistics on the publication output and citation impact of a researcher. All citations are counted except for self citations. Self citations are reported separately, with a distinction between author self citations (i.e., citations by a researcher to his/her own publications) and co-author self citations (i.e., citations by co-authors of a researcher to their joint publications). The trend analysis in the Citation Impact I report shows the number of citations received by a researcher per year.
Citation Impact II report
Like the Citation Impact I report, the Citation Impact II report provides statistics on the publication output and citation impact of a researcher. One of the differences between the two reports is that instead of all WoS-indexed publications of a researcher the Citation Impact II report includes only publications of the WoS document types article and review, which are considered to be the two most significant document types. This for instance means that book reviews, editorials, and letters to the editor are not included. Furthermore, instead of counting all citations, the report only counts citations received within a fixed time period (by default four years) after the appearance of a publication. In this way, older and more recent publications are made more comparable to each other.
The advantage of the Citation Impact II report is that it provides field-normalized citation statistics. These statistics allow for comparisons of citation impact between fields with different citation practices. If the normalized number of citations of a publication is above (below) one, the publication has been cited more (less) frequently than the average of its field. For instance, if on average a researcher has received 1.5 normalized citations per publication, this means that the publications of the researcher have been cited about 50% more frequently than the average of their field. In addition to normalized citation statistics, the Citation Impact II report also provides normalized journal impact statistics. A normalized journal impact of 1.5 per publication for instance means that the publications of a researcher have appeared in journals that have received 50% more citations than the average of their field.
Another special indicator in the Citation Impact II report is the coverage indicator. This indicator is calculated as the percentage of the references in the publications of a researcher that point to publications covered by WoS. Coverage can be interpreted as an approximate measure of the degree to which WoS provides a complete bibliometric picture of a researcher. In general, the higher a researcher’s coverage, the more complete a WoS-based bibliometric profile of a researcher can be expected to be.
The trend analysis in the Citation Impact II report is different from the one in the Citation Impact I report. In the Citation Impact II report, the trend analysis does not show the number of citations received per year but rather the number of citations received (within a fixed time window) by publications that appeared in specific years.
Collaboration
The Collaboration report presents some basic statistics on the degree to which a researcher is involved in scientific collaboration, as measured by co-authored publications.
Publications
The Publications report lists all WoS-indexed publications of a researcher. For each publication, the WoS document type (article, book review, editorial material, letter, review, etc.), the publication year, the number of citations, and the field-normalized number of citations are reported. In order to get an overview of a researcher’s most frequently cited publications, it is possible to sort the publication list based on the number of citations publications have received.
