Zhang, CT. 2009. The e-Index, Complementing the h-Index for Excess Citations. PLOS ONE 4 (5): art. no.-e5429.

[Eugene Garfield]

Zhang, CT. 2009. The e-Index, Complementing the h-Index for Excess
Citations. PLOS ONE 4 (5): art. no.-e5429.

Author Full Name(s): Zhang, Chun-Ting

Language: English
Document Type: Article

Abstract: 
Background: The h-index has already been used by major citation databases to
evaluate the academic performance of individual scientists. Although
effective and simple, the h-index suffers from some drawbacks that limit its
use in accurately and fairly comparing the scientific output of different
researchers. These drawbacks include information loss and low resolution:
the former refers to the fact that in addition to h 2 citations for papers
in the h-core, excess citations are completely ignored, whereas the latter
means that it is common for a group of researchers to have an identical h-index.

Methodology/Principal Findings: To solve these problems, I here propose the
e-index, where e 2 represents the ignored excess citations, in addition to
the h 2 citations for h-core papers. Citation information can be completely
depicted by using the h-index together with the e-index, which are
independent of each other. Some other h-type indices, such as a and R, are
h-dependent, have information redundancy with h, and therefore, when used
together with h, mask the real differences in excess citations of different
researchers.

Conclusions/Significance: Although simple, the e-index is a necessary
h-index complement, especially for evaluating highly cited scientists or for
precisely comparing the scientific output of a group of scientists having an
identical h-index. X h X h X h

Reprint Address: Zhang, CT, Tianjin Univ, Dept Phys, Tianjin 300072, Peoples
R China.

E-mail Address: ctzhang at tju.edu.cn

ISSN: 1932-6203
DOI: 10.1371/journal.pone.0005429

URL: http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0005429