Compare methods

	g-Index (Egghe)	Contemporary h-Index	e-Index (Excess Citations)	hg-Index (Composite Hirsch-Egghe)
Field	Bibliometrics	Bibliometrics	Bibliometrics	Bibliometrics
Family	Process / pipeline	Process / pipeline	Process / pipeline	Process / pipeline
Year of origin	2006	2007	2009	2010
Originator	Leo Egghe	Antonis Sidiropoulos, Dimitrios Katsaros & Yannis Manolopoulos	Chun-Ting Zhang	Sergio Alonso, Francisco J. Cabrerizo, Enrique Herrera-Viedma & Francisco Herrera
Type	Author-level cumulative-citation impact index	Age-discounted author impact index	Author-level excess-citation impact index	Composite author impact index
Seminal source	Egghe, L. (2006). Theory and practise of the g-index. Scientometrics, 69(1), 131-152.	Sidiropoulos, A., Katsaros, D., & Manolopoulos, Y. (2007). Generalized Hirsch h-index for disclosing latent facts in citation networks. Scientometrics, 72(2), 253-280.	Zhang, C.-T. (2009). The e-index, complementing the h-index for excess citations. PLoS ONE, 4(5), e5429.	Alonso, S., Cabrerizo, F. J., Herrera-Viedma, E., & Herrera, F. (2010). hg-index: a new index to characterize the scientific output of researchers based on the h- and g-indices. Scientometrics, 82(2), 391-400.
Aliases	Egghe g-index, Egghe index, g index	hc-index, time-weighted h-index, age-decayed h-index	Zhang e-index, excess citation index, e index	Alonso hg-index, hg index, composite h-g index
Related	3	3	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 contemporary h-index, introduced by Sidiropoulos, Katsaros, and Manolopoulos in 2007, modifies Hirsch's h-index to reward recent scientific activity over old laurels. The plain h-index never decreases and treats a citation earned decades ago the same as one earned last year, so a researcher who has stopped publishing can coast on an aging body of work. The contemporary index assigns each paper an age-discounted score, multiplying its citation count by a factor that shrinks as the paper grows older, and then applies the usual h-index ranking criterion to these scores. The result distinguishes currently active, recently impactful researchers from those whose reputation rests on distant achievements.	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.	The hg-index, proposed by Alonso, Cabrerizo, Herrera-Viedma, and Herrera in 2010, fuses the two best-known author metrics into a single composite. The h-index is robust but ignores how heavily an author's top papers are cited, while Egghe's g-index rewards those highly cited papers but can be swayed by a single outlier. The hg-index takes the geometric mean of the two, producing a value that lies between them and inherits a balance of their strengths: it remains close to the stable h-index while still responding to the citation impact captured by g. The authors showed that the geometric mean stays nearer to the smaller, more conservative h-index than the larger g-index, tempering the latter's sensitivity to extreme papers.