The Article Influence determines the average influence of a journal's articles over the first five years after publication. It is calculated by dividing a journal's Eigenfactor Score by the number of articles in the journal, normalized as a fraction of all articles in all publications. This measure is roughly analogous to the 5-Year Journal Impact factor in that it is a ratio of a journal's citation influence to the size of the journal's article contribution over a period of five years. The meanArticle Influence Score is 1.00. A score greater than 1.00 indicates that each article in the journal has above-average influence. A score less than 1.00 indicates that each article in the journal has below-average influence.
h-index (Hirsch index)
The h-index is based on a list of publications ranked in descending order by the Times Cited. The value of h is equal to the number of papers (N) in the list that have N or more citations. It is part of the Citation Analysis in Web of Science.
To learn more about how the h-index value is calculated, read: Hirsch JE. An index to quantify an individual's scientific research output. Proc Natl Acad Sci U S A. 2005 Nov 15;102(46):16569-72.
Publish or Perish is a free downloadable software that retrieves citations using Google Scholar, and then analyzes them using a series of citation metrics.
SNIP (Source-Normalized Impact per Paper)
Citation impact is weighted based on the total number of citations in a subject field. The impact of a citation is given higher value in subject areas where citations are less likely.
An article's impact may be measured using both traditional citation metrics or through non-traditional usage metrics, called Altmetrics.
Traditional Impact Metrics examine how many times an article has been cited in other journal articles. Sources for these metrics include Google Scholar, Scopus, and Web of Science.
Altmetrics try to capture how an article is used outside the journal literature, including use in social media. For example, CINAHL provides a feature called PlumX which shows how many times a record has been viewed, downloaded, tweeted, or liked.
