Authors:Rodrigo Costas, Thed van Leeuwen, and María Bordons
This paper focuses on the study of self-citations at the meso and micro (individual) levels, on the basis of an analysis of
the production (1994–2004) of individual researchers working at the Spanish CSIC in the areas of Biology and Biomedicine and
Material Sciences. Two different types of self-citations are described: author self-citations (citations received from the
author him/herself) and co-author self-citations (citations received from the researchers’ co-authors but without his/her
participation). Self-citations do not play a decisive role in the high citation scores of documents either at the individual
or at the meso level, which are mainly due to external citations. At micro-level, the percentage of self-citations does not
change by professional rank or age, but differences in the relative weight of author and co-author self-citations have been
found. The percentage of co-author self-citations tends to decrease with age and professional rank while the percentage of
author self-citations shows the opposite trend. Suppressing author self-citations from citation counts to prevent overblown
self-citation practices may result in a higher reduction of citation numbers of old scientists and, particularly, of those
in the highest categories. Author and co-author self-citations provide valuable information on the scientific communication
process, but external citations are the most relevant for evaluative purposes. As a final recommendation, studies considering
self-citations at the individual level should make clear whether author or total self-citations are used as these can affect
phenomenon called author self-citation.
An author makes self-citation (or self-reference) when he uses one of his previously published works as a reference in a new article. In multi-authored articles, a self-citation occurs whenever the set of co
calculation of these diverse indicators accessible to a more general public.
An elaborated review on the benefits and problems of the h -index is available [ 5 ]. We will focus on the problem of self-citations, which has polarized the research
Self-citations — those where authors cite their own works — account for a significant portion of all citations. These self-references
may result from the cumulative nature of individual research, the need for personal gratification, or the value of self-citation
as a rhetorical and tactical tool in the struggle for visibility and scientific authority. In this article we examine the
incentives that underlie self-citation by studying how authors’ references to their own works affect the citations they receive
from others. We report the results of a macro study of more than half a million citations to articles by Norwegian scientists
that appeared in the Science Citation Index. We show that the more one cites oneself the more one is cited by other scholars.
Controlling for numerous sources of variation in cumulative citations from others, our models suggest that each additional
self-citation increases the number of citations from others by about one after one year, and by about three after five years.
Moreover, there is no significant penalty for the most frequent self-citers — the effect of self-citation remains positive
even for very high rates of self-citation. These results carry important policy implications for the use of citations to evaluate
performance and distribute resources in science and they represent new information on the role and impact of self-citations
in scientific communication.
of author self-citations as opposed to journal self-citations (Hartley 2009 ).
Such author self-citations contribute to the overall citation count of an article and to the impact factor of the journals in which they are cited (Anseel et al
Aksnes 2007 ). In this context, a self-citation is commonly defined as a “citation in which the citing and the cited paper have at least one author in common” (Aksnes 2003 ). In addition to self-promotion of earlier work and egotism/self aggrandizement
In studies of citation analysis, self-citations are often regarded as ‘noise’ or diversions removed from analyses (Hellsten et al. 2007 ). This situation has happened since the assessment of research or scientific
Impact factors are a widely accepted means for the assessment of journal quality. However, journal editors have possibilities
to influence the impact factor of their journals, for example, by requesting authors to cite additional papers published recently
in that journal thus increasing the self-citation rate. I calculated self-citation rates of journals ranked in the Journal
Citation Reports of ISI in the subject category “Ecology” (n = 107). On average, self citation was responsible for 16.2 �
1.3% (mean � SE) of the impact factor in 2004. The self-citation rates decrease with increasing journal impact, but even high
impact journals show large variation. Six journals suspected to request for additional citations showed high self-citation
rates, which increased over the last seven years. To avoid further deliberate increases in self-citation rates, I suggest
to take journal-specific self-citation rates into account for journal rankings.