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 | 1.7321 |
| 1999 | 5.2915 |
| 2000 | 7.0000 |
| 2001 | 9.7980 |
| 2002 | 12.9228 |
| 2003 | 15.6205 |
| 2004 | 20.4206 |
| 2005 | 25.0998 |
| 2006 | 31.1127 |
| 2007 | 35.9166 |
| 2008 | 40.7554 |
| 2009 | 45.1110 |
| 2010 | 50.2494 |
| 2011 | 55.2901 |
| 2012 | 59.8080 |
| 2013 | 65.2687 |
| 2014 | 69.9786 |
| 2015 | 74.2832 |
| 2016 | 78.7718 |
| 2017 | 82.0792 |
| 2018 | 85.7496 |
| 2019 | 89.2300 |
| 2020 | 92.2605 |
| 2021 | 95.5039 |
| 2022 | 98.5140 |
| 2023 | 101.2028 |
| 2024 | 104.1393 |
| 2025 | 104.4653 |
References
- Zhang, C.-T. (2009) The e-index, complementing the h-index for excess citations. PLoS ONE 4(5):e5429.