Our own internal research demonstrates how a high journal impact factor can be the skewed result of many citations of a few papers rather than the average level of the majority, reducing its value as an objective measure of an individual paper. [...] The majority of our papers received fewer than 20 citations. [per year] [...] the numbers quoted in calculating the impact factor are highly questionable. Try as we might, my colleagues and I cannot reconcile our own counts of citable items in Nature, several other Nature journals and indeed Science, with those used by ISI. [...] the judgement of ‘better’ is best kept independent of the impact factor. [...] for a sure assessment of an individual, there is truly no substitute for reading the papers themselves, regardless of the journal in which they appear.

young scientists may even develop bad writing habits (e.g. exaggerating implications of findings, over-simplifying analyses and conclusions, ignoring caveats) if an excessive desire to publish in high-impact journals skews their scientific judgement or publication ethics. [...] The use of publication counts and number of citations to assess academic performance do affect the publishing strategy of young scientists. Particularly, at the stage of being a post-doc, to compete for the limited number of junior faculty or equivalent research positions, one would try to maximize the number of publications and their impacts in a short time-horizon

It has always been crucial for research scientists to publish their work. There have always been 3 purposes: first, to disseminate new information so that others can learn from it; second, so that other scientists may repeat the studies, or build on them with additional observations or experiments; and only third, so that the support, financial or otherwise, for the scientist can be justified to interested parties. This third reason used to be subsidiary, but no longer; publication has become the main goal because it is the scientist’s lifeline (Lawrence 2003). This enormous change in emphasis has damaged the practice of science, has transformed the motivation of researchers, changed the way results are presented and reduced the accuracy and accessibility of the scientific literature. [...] Since scientists are now assessed, not so much by the validity, interest or quality of the work itself, but by the impact factor of the journal (Steele et al. 2006), many, if not most scientists, spend too much time and effort thinking and worrying about publication strategy. [...] Politics enervates science. [...] I predict that ‘citation-fishing and citation-bartering’ will become common practice [...] scientists will claim superiority over others if they have more citations, and this will be endorsed by bean counters everywhere [...] There are other consequences of the use of numerical measures: given that meeting them rewards aggressive, acquisitive and exploitative behaviour (Lawrence 2002, Lawrence 2003, Montgomerie & Birkhead 2005), their use will select for scientists with these characteristics. [...] grant applications do not describe what you will actually do but are in reality an ingenuity and knowledge test in which honesty is little valued; they amount to an attempt to demonstrate that one knows what one is doing and can divine what the outcomes of experiments will be and assess what might be risky to reveal.

Our paper supports Lawrence’s (2007, p. R583) view that impact factors and citations are ‘dodgy evaluation criteria’, and we strongly advise against a system that wholly relies upon them to evaluate a scientist’s contribution.