Revista Chilena de Historia Natural 83 (2): 219-227, 2010
COMMENTARY
The I-index, a new estimator of the impact of scientific productivity: Ecologists from Chile as
study case
Hirsch proposed in 2005 the h-index, which integrates in a single number the impact of
scientific output of a researcher, considering both the quantity of published articles and the citations received. It has been
demonstrated that the number of coauthors in an article and the frequency of self-citations of the researcher may affect the scientific
indices. In this study we propose a new indicator of the impact of scientific output: the I-index, which is based on the h-index, correcting
for the number of coauthors of each article and the proportion of allo-citations of the researcher. In addition, we introduce the index’s
standardization by scientific age (time in years since the first publication, Is-index). We evaluated the variation of I-index with
chronological age (age classes), geographical location (Santiago vs. Regions) and gender of researchers. We also evaluated how
these patterns vary if only the top ten of each age class are considered, and if the Isindex is used. The sample group consisted of 120
researchers in ecological sciences (sensu lato). Results show that older researchers have significantly higher I-index values and that
this difference is greater when the top ten group is considered. Researchers from Santiago have higher I-index values than those from
regions. However, the opposite trend is found when the top ten young researchers are considered. Although no difference between
male and female researchers was detected when the whole data set is considered, the top ten male researchers have greater I-index
values. Standardization of the I-index for scientific age changes the upper ranking of scientific output. The proposed index has the
advantage of being an indicator that: i) better reflects the individual contribution of a researcher, ii) it is not feasible to manipulate it via
self-citations, iii) it is not an integer number, hence allowing a more precise discrimination, and iv) the standardized version allows the
comparison of the research output impact of scientists of different ages. We propose to include the I index in assessments for
academic jobs, promotions and prizes.
Key words:
Chile, h-index,
indicators, research, scientific output
