χ-index
The χ-index (Fenner et al. 2018) is the square-root of the size of the largest rectangle which can fit under the citation curve; similar to how the h-index is the size of the largest square. It is the square-root of the rec-index.
Example
Publications are ordered by number of citations, from highest to lowest.
| Citations (Ci) | 59 | 26 | 16 | 11 | 11 | 10 | 4 | 3 | 3 | 2 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rank (i) | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
| i×Ci | 59 | 52 | 48 | 44 | 55 | 60 | 28 | 24 | 27 | 20 | 11 | 12 | 13 | 0 | 0 | 0 | 0 | 0 |
The largest rectangle which can fit under the citation curve has an area of 60, the square-root of which is χ = 7.746.
History
| Year | χ |
|---|---|
| 1997 | 1.4142 |
| 1998 | 3.0000 |
| 1999 | 5.0990 |
| 2000 | 5.9161 |
| 2001 | 7.7460 |
| 2002 | 10.0000 |
| 2003 | 11.3137 |
| 2004 | 16.0000 |
| 2005 | 18.9737 |
| 2006 | 24.0832 |
| 2007 | 27.7489 |
| 2008 | 30.3974 |
| 2009 | 32.8634 |
| 2010 | 35.5809 |
| 2011 | 38.8201 |
| 2012 | 42.4264 |
| 2013 | 45.8912 |
| 2014 | 48.7442 |
| 2015 | 51.7494 |
| 2016 | 54.7996 |
| 2017 | 56.7803 |
| 2018 | 57.8014 |
| 2019 | 59.8665 |
| 2020 | 62.2093 |
| 2021 | 64.5755 |
| 2022 | 64.8074 |
| 2023 | 66.6183 |
| 2024 | 67.9706 |
| 2025 | 68.3813 |
References
- Fenner, T., M. Harris, M. Levene, and J. Bar-Ilan (2018) A novel bibliometric index with a simple geometric interpretation. PLoS ONE 13(7):e0200098.