Past research suggests that such uses are inappropriate. To emphasize some of the limitations of the impact factor, Curry’s team plotted the distribution of citations for articles published in 2013–14 in 11 journals, including Science, Nature, eLife and three Public Library of Science (PLoS) journals. These are the citations used to calculate the 2015 impact factors. Curry’s co-authors include senior employees at SpringerNature, eLife, PLoS, the Royal Society (which publishes several journals) and EMBO Press, and Marcia McNutt, who stepped down on 1 July from her role as editor-in-chief of Science.
Most of the papers garnered fewer citations than the impact factor for their journal: 74.8% of Nature articles were cited below its impact factor of 38.1, and 75.5% of Science papers were cited fewer than 35 times in two years (its impact factor was 34.7). PLoS Genetics had the lowest proportion of papers with fewer citations than its impact factor of 6.7, at 65.3%.
Highly cited papers explain this disconnect. Nature’s most cited paper in the analysis was referenced 905 times and Science’s 694 times. PLoS ONE’s biggest paper accrued 114 citations, versus its impact factor of 3.1.