Citation Analysis

Citation analysis: A wide-ranging area of bibliometrics that studies the citations to and from documents.  Citation analysis applies various techniques such as citation counts that can help establish scholarship influence and patterns. Unlike common database searching by Author or Subject, citation searching tracks where works (articles, books, conference proceedings, etc) have been cited by other authors.

Citation count/ citation rate/ citation frequency: often refers to the number of citations an author, document, or journal has received during a certain period of time. If expressed as a ratio, especially for a group of documents published by a particular journal, citation rate becomes equivalent to impact factor. 

Impact factor: A measure of the importance or influence of a group of documents. Speaking imprecisely, impact factor is the number of citations received by an average document in the group.

Journal Impact Factor: The number of cited articles in a particular journal may be used to demonstrate the relative importance of that journal within a discipline or specialty area. This "journal impact factor" is tracked by InCites, which is associated with Web of Science and is proprietary. Other measures (e.g. the h-index) can also be used to evaluate the impact that a journal has in its field. Scopus and SciMago compete with InCites with a similar metric called the SJR.

Eugene Garfield, the origin of the idea of an impact factor in 1955, has authored an article that explains its history. Garfield E. The History and Meaning of the Journal Impact Factor. JAMA. 2006;295(1):90-93. doi:10.1001/jama.295.1.90.

Counting the number of times a publication has been cited is attractive because it is concrete data. However, citation analysis tools have extensive limitations discussed below.  Results should therefore be used in conjunction with other indicators of quality when presented in support of a case for promotion and tenure.

Keep the following caveats in mind when evaluating research quality using citation indicators:

• No citation database is all inclusive. Citation databases do not track citations for every journal. Journals from some fields may be poorly represented and citation results will reflect this disparity between fields.
• Some disciplines have less extensive citation activity than others. Most research work in scientific fields attracts far more citations than does research in many humanities fields.
• Recent research may not be cited. The time lag or immediacy factor varies significantly in different fields. Some scientific fields experience rapid citation at the research front, while others take years for research to be noticed.
• Citation rates can be influenced by such factors as few authors citing one another or by an author's high rates of self-citation. Poor quality papers may have a high citation count because they are cited while being criticized or refuted. 
• Entries in citation databases may not be standard or follow a consistent name-authority scheme. Errors made by citing authors or by indexers may make it difficult to retrieve complete citation counts.
• Common authors' name forms are very difficult to separate from other similar names (especially in citation indexes that rely on initials instead of full names). Advances in indexing quality, however, have improved the identification of authors' identities. Searching by title of a work as opposed to author name is a sure way of avoiding this problem.