eprintid: 2376
rev_number: 10
eprint_status: archive
userid: 27
dir: disk0/00/00/23/76
datestamp: 2014-11-24 08:25:15
lastmod: 2014-11-24 08:25:15
status_changed: 2014-11-24 08:25:15
type: article
metadata_visibility: show
creators_name: Petersen, Alexander M.
creators_name: Succi, Sauro
creators_id: alexander.petersen@imtlucca.it
creators_id: 
title: The Z-index: A geometric representation of productivity and impact which accounts for information in the entire rank-citation profile
ispublished: pub
subjects: HA
subjects: Q1
subjects: Z665
divisions: EIC
full_text_status: public
keywords: Science of science; Citation impact; Rank stability; h-Index
abstract: We present a simple  generalization of Hirsch's h-index, Z \equiv \sqrt{h^{2}+C}/\sqrt 5, where C is the total number of citations. Z is aimed at correcting  the potentially excessive penalty made by h on a scientist's highly cited papers, because for the majority of scientists analyzed, we find the excess citation fraction (C-h^{2})/C  to be distributed closely around the value 0.75, meaning that 75 percent of the author's impact is neglected. Additionally, Z is less sensitive to local changes in a scientist's citation profile, namely perturbations  which increase h while only marginally affecting C. Using real career data for 476 physicists careers and 488 biologist careers, we analyze both the distribution of Z and the rank stability of Z with respect to the Hirsch index h and the Egghe index g. We analyze careers distributed across a wide range of total impact, including top-cited physicists and biologists for benchmark comparison. In practice, the Z-index requires the same information needed to calculate h and could be effortlessly  incorporated within career profile 
databases, such as Google Scholar and ResearcherID. Because Z incorporates information from the entire publication profile while being more robust than h and g to local perturbations, we argue that Z is better suited for ranking comparisons in academic  decision-making scenarios comprising a large number of scientists. 
date: 2013-10
date_type: published
publication: Journal of Informetrics
volume: 7
number: 4
publisher: Elsevier
pagerange: 823-832
id_number:         doi:10.1016/j.joi.2013.07.003
refereed: TRUE
official_url: http://www.sciencedirect.com/science/article/pii/S1751157713000564
citation:   Petersen, Alexander M. and Succi, Sauro  The Z-index: A geometric representation of productivity and impact which accounts for information in the entire rank-citation profile.  Journal of Informetrics, 7 (4).  pp. 823-832.       (2013)  
document_url: http://eprints.imtlucca.it/2376/1/1308.5752v1.pdf