Abstract
The pursuit of simple, yet fair, unbiased, and objective measures of
researcher performance has occupied bibliometricians and the research
community as a whole for decades. However, despite the diversity of
available metrics, most are either complex to calculate or not readily
applied in the most common assessment exercises (e.g., grant assessment,
job applications). The ubiquity of metrics like the h -index
(h papers with at least h citations) and its
time-corrected variant, the m -quotient (h -index ÷ number
of years publishing) therefore reflect the ease of use rather than their
capacity to differentiate researchers fairly among disciplines, career
stage, or gender. We address this problem here by defining an easily
calculated index based on publicly available citation data (Google
Scholar) that corrects for most biases and allows assessors to compare
researchers at any stage of their career and from any discipline on the
same scale. Our ε ′-index violates fewer statistical assumptions
relative to other metrics when comparing groups of researchers, and can
be easily modified to remove inherent gender biases in citation data. We
demonstrate the utility of the ε ′-index using a sample of 480
researchers with Google Scholar profiles, stratified evenly into eight
disciplines (archaeology, chemistry, ecology, evolution and development,
geology, microbiology, ophthalmology, paleontology), three career stages
(early, mid-, late-career), and two genders. We advocate the use of theε ′-index whenever assessors must compare research performance
among researchers of different backgrounds, but emphasize that no single
index should be used exclusively to rank researcher capability.