The ** g-index** is an author-level metric suggested in 2006 by Leo Egghe.

^{[1]}The index is calculated 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

*g*

^{2}citations.

It can be equivalently defined as the largest number *n* of highly cited articles for which the average number of citations is at least *n*. This is in fact a rewriting of the definition

as

The *g*-index is an alternative for the older *h*-index, which does not average the numbers of citations. The *h*-index only requires a minimum of n citations for the least-cited article in the set and thus ignores the citation count of very highly cited papers. Roughly, the effect is that *h* is the number of papers of a quality threshold that rises as h rises; *g* allows citations from higher-cited papers to be used to bolster lower-cited papers in meeting this threshold. Therefore, in all cases *g* is at least *h*, and is in most cases higher.^{[1]} However, unlike the *h*-index, the *g*-index saturates whenever the average number of citations for all published papers exceeds the total number of published papers; the way it is defined, the *g*-index is not adapted to this situation.

The *g*-index has been characterized in terms of three natural axioms by Woeginger (2008).^{[2]} The simplest of these three axioms states that by moving citations from weaker articles to stronger articles, one's research index should not decrease. Like the *h*-index, the *g*-index is a natural number and thus lacks in discriminatory power. Therefore, Tol (2008) proposed a rational generalisation.^{[3]}^{[clarification needed]}

Tol also proposed a collective *g*-index.

- Given a set of researchers ranked in decreasing order of their
*g*-index, the*g*_{1}-index is the (unique) largest number such that the top*g*_{1}researchers have on average at least a*g*-index of*g*_{1}.

## References

- ^
^{a}^{b}Egghe, Leo (2006). "Theory and practise of the*g*-index".*Scientometrics*.**69**(1): 131–152. doi:10.1007/s11192-006-0144-7. hdl:1942/981. **^**Woeginger, Gerhard J. (2008). "An axiomatic analysis of Egghe's g-index".*Journal of Informetrics*.**2**(4): 364–368. doi:10.1016/j.joi.2008.05.002.**^**Tol, Richard S.J. (2008). "A rational, successive g-index applied to economics departments in Ireland".*Journal of Informetrics*.**2**(2): 149–155. doi:10.1016/j.joi.2008.01.001. preprint