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

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.1