a-index
The a-index (Jin 2006; Rousseau 2006) is used to describe the citations within the h-index core itself, being simply the average number of citations per core publication, or
$$a=\frac{C^H}{h}=\frac{\sum\limits_{i=1}^{h}{C_i}}{h}.$$The minimum value of a is h (since every one of the h publications must have at least h citations).
History
| Year | a |
|---|---|
| 1997 | 1.0000 |
| 1998 | 4.5000 |
| 1999 | 12.3333 |
| 2000 | 14.4000 |
| 2001 | 21.3333 |
| 2002 | 27.3750 |
| 2003 | 31.9091 |
| 2004 | 46.2500 |
| 2005 | 56.1333 |
| 2006 | 72.0000 |
| 2007 | 86.5263 |
| 2008 | 99.6190 |
| 2009 | 105.0800 |
| 2010 | 121.5769 |
| 2011 | 132.9310 |
| 2012 | 143.2188 |
| 2013 | 161.5152 |
| 2014 | 177.6471 |
| 2015 | 192.3429 |
| 2016 | 211.9143 |
| 2017 | 218.3514 |
| 2018 | 235.0270 |
| 2019 | 251.4054 |
| 2020 | 261.2368 |
| 2021 | 265.8500 |
| 2022 | 276.2439 |
| 2023 | 284.0952 |
| 2024 | 286.2143 |
References
- Jin, B. (2006) h-index: An evaluation indicator proposed by scientist. Science Focus 1(1):8–9.
- Rousseau, R. (2006) New developments related to the Hirsch index. Science Focus 1(4):23–25.