Citing practices in ecology: can we believe our own words?

Peer-reviewed articles are the foundation of modern ecological science. An essential component of most ecology papers is a clear, well-crafted argument that builds upon the existing research base within the subject area in question and substantiates important assumptions, technical information and opinions by accurately identifying (i.e. citing) the source material. Despite the central role of citing references in the writing of research papers, there have been no studies to date that assess the suitability and fidelity of citations in ecology journals. Anecdotal evidence certainly suggests that citation malpractice is widespread. Many of us have encountered instances where the support of an assertion by the cited reference proves to be ambiguous, nonexistent, or even contradictory (often we only notice this when our own work has been mis-cited!). A related practice is the citing of ‘‘empty’’ references (Harzing 2002), also known as ‘‘lazy author syndrome’’ (Gavras 2002), where the citation actually attributes a finding or an opinion to a secondary source such as a review paper, editorial, etc. But how pervasive is citation malpractice and how can it be controlled? We randomly selected three papers from each of the two most recent issues (prior to April 2006) of 51 journals listed under ‘‘Ecology’’ in the Science Citation Index (all with an impact factor 1) to examine the appropriateness and accuracy of citations used. From each of the 306 papers (the ‘‘primary articles’’) we then selected randomly one citation from the reference list (the ‘‘cited article’’) and identified the assertion it was purportedly supporting. To avoid ambiguity we only used assertions supported by a single citation and, to reduce potential bias from especially errant authors, only one citation per primary article was selected. The cited article was then obtained and examined carefully (independently by three of the authors: PT, DY and LD) and its appropriateness was categorised into one of four groups by a majority decision (Table 1). At all stages of the study, papers obtainable only through the National University of Singapore digital library system were used. As just six articles per journal were selected, among-journal trends were not examined. We found that the original assertion was ‘‘clearly supported’’ by the citation in 76.1% of the cases; the support was ‘‘ambiguous’’ in 11.1% of the cases; and the citation did ‘‘not support’’ the original statement in 7.2% of the cases. The remaining 5.6% of the cases were classified as ‘‘empty’’. How do these mis-citation rates compare with other disciplines? One well-publicised example from physics and engineering (Ball 2002, Muir 2002, Simkin and Roychowdhury 2003) analysed how misprinted citations are propagated through the scientific literature and concluded that as many as 80% of all cited papers are not read by the authors citing them (Simkin and Roychowdhury 2003). This result, however, is most probably an overestimation (copying citations from other sources is not necessarily associated with whether those papers have actually been read). A number of biomedical studies have used an approach similar to our own, although they applied the analogous categories ‘‘major error’’ and ‘‘minor error’’ rather than ‘‘no support’’ and ‘‘ambiguous’’. Combined error rates found by Fenton et al. 2000 (17%) and Lukić et al. 2004 (19%) are comparable to our result of 18.3% for ‘‘no support’’ plus ‘‘ambiguous’’, though other results for medical journals range from 12.3% (Gosling et al. 2004) to 35.2% (Goldberg et al. 1993). To our knowledge, empty citation data are absent for all the sciences. Various proximate factors could be responsible for misappropriation of citations. Many instances will be genuine mistakes where the article has been misread or misunderstood or, through the long process of writing a Oikos 116: 1599 1601, 2007 doi: 10.1111/j.2007.0030-1299.15992.x, Copyright # Oikos 2007, ISSN 0030-1299