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Scholarly Impact Research Guide (Matas)

This guide provides information and instruction on the different types of metrics used to evaluate and locate metrics on scholarly impact.

Select Definitions and Metrics

Cited reference searching can be used to find out if an article, book, journal, or particular author has been cited by another work. The more citations, the greater the academic impact.

h-index:  based on the highest number of papers included that have had at least the same number of citations. The value of h is equal to the number of papers (N) in the list that have N or more citations. h-index should be used only within the context of a field or subfield, and not across disciplines or subject areas. 

e.g., If a Physicist has published 100 papers in her 40 year career, and 30 of those papers have been cited at least 30 times, then her h-index would be 30.

Individual h-index (original): divides the standard h-index by the average number of authors in the articles that contribute to the h-index, in order to reduce the effects of co-authorship. 

Individual h-index (PoP variation): instead of dividing the total h-index, it first normalizes the number of citations for each paper by dividing the number of citations by the number of authors for that paper, then calculates the h-index of the normalized citation counts.

Cited reference searching: used to find out if an article, book, journal, or particular author has been cited by another work. 

g-index: based on the distribution of citations received by a given researcher's publications, such that given a set of articles ranked in decreasing order of the number of citations that they received, the g-index is the unique largest number such that the top g articles received together at least g2 citations.

The g-index is an alternative for the older h-index, which doesn’t average the numbers of citations

Journal Metrics can help track citation patterns within journals and determine which journals are highly-cited.

Journal Impact Factor: the average number of times, in the past two years, that articles from a journal have been cited in the Journal Citation Reports (JCR). Most commonly used Journal Impact Metric.

5-Year Journal Impact Factor: the average number of times articles from the journal published in the past five years have been cited in the JCR year. It is calculated by dividing the number of citations in the JCR year by the total number of articles published in the five previous years.

Journal Immediacy Index: Citations to articles from the current year, divided by the total number of articles from the current year. 

Eigenfactor Score: Similar to the 5-Year Journal Impact Factor, but weeds out journal self-citations.  Includes both the hard sciences and the social sciences.

Article Influence Score: the average influence of a journal's articles over the first five years after publication. The Eigenfactor score divided by the number of articles published in journal.  Mean score is 1.

SJR - SCImago Journal Rank: Doesn't consider all citations of equal weight; the prestige of the citing journal is taken into account.

h5-index: the h-index for articles published in the last 5 complete years. It is the largest number h such that h articles published in 2010-2014 have at least h citations each

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