Myriad bibliometric indices have been developed to measure an author’s scientific contributions. Currently, the author-specific ‘Hirsch-index’ or h-index, defined as the number of publications, ‘h’, that have at least ‘h’ citations, is a commonly employed metric.Citation1,Citation2 Since its creation, multiple criticisms have been levied against the measure.Citation1,Citation3,Citation4 For one, the h-index is heavily influenced by career duration. Younger researchers with a few high-impact publications will have a lower h-index than older researchers with numerous, low-impact publications. For example, if a young author has five publications with 100 citations each, their h-index (5) will be lower than the h-index (10) of an older author who has 10 publications with 10 citations each. Another significant criticism is that the h-index must be contextualized to its field to be meaningful. Indeed, comparisons of researchers in more highly cited specialties, such as internal medicine, with researchers in less frequently cited specialties, such as ophthalmology, would be insensible.Citation1,Citation4 Similar would be the case with subspecialties, for example, ‘retina’ and ‘Oculoplasty’.
To improve on these limitations, the National Institutes of Health (NIH) proposed a novel metric, the relative citation ratio (RCR), in 2015.Citation5 As an article-specific measure, the RCR is defined as the yearly number of citations an article receives divided by the yearly number of citations accrued by NIH-funded publications in the same field. Each article’s field is dynamically determined by its co-citation network, enabling reasonable multidisciplinary comparisons of scholarly output.Citation5 The RCR may be used to derive author-specific metrics. The mean RCR is defined as the average of an author’s article specific RCR scores, thereby enabling assessments of their research impact by eliminating the influence of publication number. This measure is useful when considering two investigators with divergent career lengths. Comparatively, the weighted RCR is defined as the sum of an author’s article-level RCR scores, therefore encapsulating their lifetime scholarly contributions. Thus, it is useful when determining the productivity of researchers over their entire careers.
As a function of its relative novelty, benchmark data on the RCR remain limited, particularly among medical specialists. Investigations have been conducted in neurosurgery, radiation oncology, and ophthalmology. Their findings emphasized the measure’s validity, as it correlated with faculty characteristics commonly associated with greater academic output.Citation6–10
Article-specific RCR scores and the author-specific mean and weighed RCR are accessible through the public NIH iCite database (https://icite.od.nih.gov), which encompasses all articles indexed on PubMed from 1980 to the present. Percentiles for all PubMed-indexed publications and NIH-funded publications are detailed in this database; the median RCR for all publications is 0.37 and for NIH-funded publications is 1. Another source is the Dimensions database (https://www.dimensions.ai), which has the advantage of curating easily searchable profiles for individual scholars, unlike the iCite database. However, it must be noted that, at present, only mean RCR scores are available.
The RCR is not without its limitations. Similar to the h-index and its derivatives, the RCR does not consider authorship position when assessing research contributions; in other words, first and senior authors are accorded the same recognition for an article even if they may have provided variable input.Citation1,Citation3 Another criticism is that this measure may be influenced by self-citations, although that effect is likely quite limited.Citation5
Further benchmarking studies of the RCR are encouraged to understand the bibliometric better. Regardless, the RCR offers potential as another modality to measure research impact and productivity.
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References
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