Author-level metrics: Its impact on scholarly output evaluation among various publication metrics

Abstract

Publication metrics indicate the visibility and reach of a research publication. The metrics can be at article-level, author-level, and journal-level to measure the scholarly output and its impact.¹ Bibliometrics is the use of statistical methods to analyze various publications mostly used in the field of library and information science; whereas, scientometrics is the sub-field concerned with the science of metrics for the measurement and analysis of scholarly publications.^2,3 Readers are not always well informed about the various publication metrics, and use them without knowing how to interpret them, their strength and limitations.^4,5

The Internet has revolutionized the dissemination, visibility, and impact of documented evidence available on the Web. The author-level metrics (ALmetrics) provides a measure for the research output of an individual author.⁶ It summarizes and aggregates the impact of an author's publications by using metrics like h-index (Hirsch-index⁷, calculated from the number of articles N by an author that have each received at least N citations), i10-index (measures the number of publications with at least 10 citations, Google Scholar), g-index (an improvement of h-index by giving more weight to highly-cited articles), e-index (differentiates between scientists with similar h-indices but different citation patterns) and others.⁸

The h-index (proposed by J.E. Hirsch in 2005) is a well-accepted metric to assess the scientific impact of an individual author and/or institution due to its simplicity for cumulative research output to indicate a number of papers (h) with at least h citations, e.g. h-index 9 means that among all publications by an author, 9 publications have at least 9 citations each.^9,10 Various other new additions are proposed to complement the h-index to minimize its shortcomings in calculations of the index due to co-authors, self/collaborative citation, publication age, publication count, etc.¹¹ The h-core is a contextualized evaluation considered more useful.¹² Combination of newer variants help complement and eliminate some of the limitations of h-index, for example, R-index (to measure citation intensity of h-score) and AR-index (to include the age of publications).^{13 14} The w-index is another simple and useful improvement to the h-index to assess the integrated impact of a researcher's work.¹⁵ The rh-index (robust h-index) adds value for the self- and collaborative citation.¹⁶