Compare methods

	g-Index (Egghe)	e-Index (Excess Citations)
Field	Bibliometrics	Bibliometrics
Family	Process / pipeline	Process / pipeline
Year of origin	2006	2009
Originator	Leo Egghe	Chun-Ting Zhang
Type	Author-level cumulative-citation impact index	Author-level excess-citation impact index
Seminal source	Egghe, L. (2006). Theory and practise of the g-index. Scientometrics, 69(1), 131-152.	Zhang, C.-T. (2009). The e-index, complementing the h-index for excess citations. PLoS ONE, 4(5), e5429.
Aliases	Egghe g-index, Egghe index, g index	Zhang e-index, excess citation index, e index
Related	3	3
Summary	The g-index, introduced by Leo Egghe in 2006, is an author-level bibliometric indicator designed to repair a structural weakness of Hirsch's h-index: its insensitivity to the size of the most-cited papers. Where the h-index caps the credit any single paper can earn at h, the g-index lets exceptionally cited articles raise an author's score. It is defined as the largest number g such that the g most-cited papers together accumulate at least g-squared citations. Because it rests on cumulative rather than per-paper citation counts, the g-index always equals or exceeds the h-index and rewards researchers whose impact is concentrated in a few landmark works as well as those with broad, steady output.	The e-index, proposed by Chun-Ting Zhang in 2009, isolates the citations that the h-index throws away. Inside the h-core of an author's h most-cited papers, the h-index implicitly credits each paper with only h citations and discards everything above that, even though top papers may have far more. The e-index recovers exactly this surplus: it is the square root of the difference between the total citations of the h-core and the h-squared citations that the h-index already accounts for. Zhang designed it as a complement rather than a replacement for the h-index, so that the pair (h, e) together describe both the size of an author's productive core and the concentration of excess impact within it.