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.