Misconceptions surrounding the relationship between journal impact factor and citation distribution in veterinary medicine

Objective

To define the relationship between journal impact factor (JIF) and citation distribution in veterinary journals. Citation distribution is a summary of the number of citations of individual papers published in a defined period, and JIF is said to represent the mean number of citations received by a paper published in a given journal. JIF is criticized for promoting unimportant differences between journals, exaggerating small differences in journal citation distributions by misrepresenting a skewed citation distribution. The hypothesis was that veterinary journals have a skewed citation distribution and that median citation rates between journals would be smaller than that indicated by JIF.

Study design

Bibliometric study.

Animals

None.

Methods

A published method was used to generate journal citation reports from a commercial database, with search limits set for document (‘article’ and ‘review’) and the 2 year citation window of interest. Citation distributions [median (range)] and cumulative citations were calculated for Veterinary Anaesthesia and Analgesia (Vet Anaesth Analg, 2007–2017), 11 preselected subject- and species-specific and general veterinary journals (2016) and veterinary journals from the top (n = 10) and bottom (n = 10) of the Veterinary Sciences category ranking (2016) with a 10 year publication record.

Results

Citation distributions were right-skewed for all journals, with 15–20% of papers contributing approximately 50% of citations. For Vet Anaesth Analg, the median citation distribution [1 (0–2)] did not change despite JIF ranging from 1.044 to 2.064 between 2007 and 2017. Calculated median citation rates revealed minimal differences between journals, with only three groups identified: bottom (median citation 0), preselected (median citation 1) and top (median citation 2) journals. These groups represent over 100 places in the JIF (0.316–3.148) ranking.

Conclusions

Ranking veterinary journals according to JIF is misleading, exaggerating differences while concealing minimally different citation distributions.