e-index
The e-index (Zhang 2009) is simply a measure of the excess citations in the h-index core beyond those necessary to produce the core itself. It is measured as:
$$e=\sqrt{C^H-h^2}=\sqrt{\sum\limits_{i=1}^{h}{C_i}-h^2}.$$Graphically, it is the square-root of the total citations within the upper part of the citation curve.
History
| Year | e |
|---|---|
| 1997 | 0.0000 |
| 1998 | 2.2361 |
| 1999 | 5.2915 |
| 2000 | 6.8557 |
| 2001 | 9.5917 |
| 2002 | 12.4499 |
| 2003 | 15.1658 |
| 2004 | 20.2731 |
| 2005 | 24.8395 |
| 2006 | 30.5778 |
| 2007 | 35.8190 |
| 2008 | 40.6325 |
| 2009 | 44.7437 |
| 2010 | 49.8498 |
| 2011 | 54.8999 |
| 2012 | 59.6574 |
| 2013 | 65.1230 |
| 2014 | 69.8856 |
| 2015 | 74.2092 |
| 2016 | 78.6893 |
| 2017 | 81.9146 |
| 2018 | 85.5979 |
| 2019 | 89.0674 |
| 2020 | 92.1032 |
| 2021 | 95.0474 |
| 2022 | 98.2090 |
| 2023 | 100.8365 |
| 2024 | 101.2768 |
References
- Zhang, C.-T. (2009) The e-index, complementing the h-index for excess citations. PLoS ONE 4(5):e5429.