Skewed citation distribution is a major limitation of the Journal Impact Factor (JIF) representing an outlier-sensitive mean citation value per journal The present study focuses primarily on this phenomenon in the medical literature by investigating a total of n = 982 journals from two medical categories of the Journal Citation Report (JCR). In addition, the three highest-ranking journals from each JCR category were included in order to extend the analyses to non-medical journals. For the journals in these cohorts, the citation data (2018) of articles published in 2016 and 2017 classified as citable items (CI) were analysed using various descriptive approaches including e.g. the skewness, the Gini coefficient, and, the percentage of CI contributing 50% or 90% of the journal’s citations. All of these measures clearly indicated an unequal, skewed distribution with highly-cited articles as outliers. The %CI contributing 50% or 90% of the journal’s citations was in agreement with previously published studies with median values of 13–18% CI or 44–60% CI generating 50 or 90% of the journal’s citations, respectively. Replacing the mean citation values (corresponding to the JIF) with the median to represent the central tendency of the citation distributions resulted in markedly lower numerical values ranging from − 30 to − 50%. Up to 39% of journals showed a median citation number of zero in one medical journal category. For the two medical cohorts, median-based journal ranking was similar to mean-based ranking although the number of possible rank positions was reduced to 13. Correlation of mean citations with the measures of citation inequality indicated that the unequal distribution of citations per journal is more prominent and, thus, relevant for journals with lower citation rates. By using various indicators in parallel and the hitherto probably largest journal sample, the present study provides comprehensive up-to-date results on the prevalence, extent and consequences of citation inequality across medical and all-category journals listed in the JCR.

倾斜的引文分布是代表每个期刊的离群值敏感平均引文值的期刊影响因子（JIF）的主要局限性。本研究主要通过研究n =来自《期刊引证报告》（JCR）的两个医学类别的982种期刊。此外，还包括每个JCR类别中排名最高的三种期刊，以便将分析范围扩展到非医学期刊。对于这些队列中的期刊，使用各种描述性方法（包括偏度，基尼系数和贡献50的CI百分比）分析了2016年和2017年被列为可引用项目（CI）的文章的引文数据（2018） ％或90％的期刊引用。所有这些措施都清楚地表明分布不均，偏斜，高被引用的文章成为异常值。％CI贡献了该期刊引文的50％或90％，与之前发表的研究相一致，中位值为13-18％CI或44-60％CI产生了该期刊引文的50％或90％，分别。用中位数代替平均引文值（对应于JIF）以表示引文分布的集中趋势，结果导致数值显着降低，范围为− 30至− 50％。在一种医学期刊类别中，多达39％的期刊显示中位引用数为零。对于这两个医学队列，基于中位的期刊排名与基于均值的排名相似，尽管可能的排名位置减少到13。平均引文与引文不平等性的相关性表明，每个期刊的引文分布不均是更引人注目，因此与引用率较低的期刊相关。通过并行使用各种指标和迄今为止最大的期刊样本，