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) | 57 | 26 | 16 | 12 | 11 | 10 | 4 | 3 | 2 | 1 | 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 | 57 | 52 | 48 | 48 | 55 | 60 | 28 | 24 | 18 | 10 | 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 | 5.2915 |
| 2000 | 5.9161 |
| 2001 | 7.7460 |
| 2002 | 10.7238 |
| 2003 | 11.6190 |
| 2004 | 16.3095 |
| 2005 | 19.5959 |
| 2006 | 24.1868 |
| 2007 | 27.5681 |
| 2008 | 30.4959 |
| 2009 | 32.9545 |
| 2010 | 35.5809 |
| 2011 | 38.8844 |
| 2012 | 42.7083 |
| 2013 | 46.1844 |
| 2014 | 49.3559 |
| 2015 | 52.0769 |
| 2016 | 55.3895 |
| 2017 | 57.1314 |
| 2018 | 58.0259 |
| 2019 | 59.9833 |
| 2020 | 62.2736 |
| 2021 | 63.9922 |
| 2022 | 64.9230 |
| 2023 | 66.0908 |
| 2024 | 67.4537 |
| 2025 | 67.4537 |
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.