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Revista Chilena de Historia Natural 83 (2): 219-227, 2010
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

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