1. H-indexes & Aging Peter Ingwersen Royal School of LIS, Denmark
University College, Oslo, Norway, 2011

2. H-indexes (2005 …)
Hirsch's h-index Proposed by J.E. Hirsch in his paper An index to quantify an individual's scientific research output, arXiv:physics/ v5 29 Sep It aims to provide a robust single-number metric of an academic's impact, combining quality with quantity. h is that rank number of item(s) which, sorted by citations, at least have received h citations over a given period of time
h = 20: 20 items have received ≥ 20 cits
Ingwersen
2011

3. G-index – etc.
Egghe's g-index Proposed by Leo Egghe in his paper Theory and practice of the g-index, Scientometrics, Vol. 69, No 1 (2006), pp
It aims to improve on the h-index by giving more weight to highly-cited articles.
Zhang's e-index published in his paper The e-index, complementing the h-index for excess citations, PLoS ONE, Vol 5, Issue 5 (May 2009), e5429.
The e-index is the (square root) of the surplus of citations in the h-set beyond h2, i.e., beyond the theoretical minimum required to obtain a h-index of 'h'. The aim of the e-index is to differentiate between scientists with similar h-indices but different citation patterns.
Ingwersen
2011

4. H-index … etc.
Can be demonstrated by Google Scholar or Web of Science (sort by citations)
The derivated indexes are more cumbersome to calculate in WoS
Ingwersen
2011

5. Ageing of journals or articles
Cited half-life - diachronic:
Acumulate citations forward in time by year:
yrs
Citations
Cum: †
1/2 life= 132/2 = 66 = ca. 4,2 years
Ingwersen
2011

6. Ageing of journals or articles – 2
Ingwersen
2011

7. Synchronic Cited Half-life
This is shown in JCR (see earlier/next slide)
It counts citations given in present year to a journal for each year’s publications back in time!
Ingwersen
2011

8. JASIST 2
Ingwersen
2010

9. Ingwersen
2011