The H Index was developed by
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.
The h-index is calculated by the number of publications and the number of citations received. For example, an h index of 20 means there are 20 items, that have 20 citations or more.
J. E. Hirsch . An index to quantify an individual's scientific research output. PNAS November 15, 2005 vol. 102 no. 46
Average h-index may vary between different disciplines.
Average h-index may vary by identification the name of the author.
Self-citations may influence on h-index.
Cross-disciplinary research may produce fewer citations.
Researchers who produce a small number of influential papers with high citation rates will have low h-index if citations to their other papers are low, even though their contribution to a discipline may be high.
Researchers with short publishing careers might appear disadvantaged by low h-indexes, even though their impact in a discipline may be high.
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