Egghe L. "Continuous, weighted Lorenz theory and applications to the study of fractional relative impact factors " INFORMATION PROCESSING & MANAGEMENT 41 (6): 1330-1359 DEC 2005

[Eugene Garfield]

E-mail Addresses: leo.egghe at luc.ac.be

Title: Continuous, weighted Lorenz theory and applications to the study of
fractional relative impact factors

Author(s): Egghe L

Source: INFORMATION PROCESSING & MANAGEMENT 41 (6): 1330-1359 DEC 2005

Document Type: Article   Language: English
Cited References: 29     Times Cited: 0

Abstract: This paper introduces weighted Lorenz curves of a continuous
variable, extending the discrete theory as well as the non-weighted
continuous model.
Using publication scores (in function of time) as the weights and citation
scores (in function of time) as the dependent variables, we can construct
an "impact Lorenz curve" in which one can read the value of any fractional
impact factor, i.e. an impact factor measured at the time that a certain
fraction of the citations is obtained or measured at the time a certain
fraction of the publications is obtained.

General properties of such Lorenz curves are studied and special results
are obtained in case the citation age curve and publication growth curve
are exponential functions. If g is the growth rate and c is the aging rate
we show that 9 deter-mines the impact Lorenz curve and also we show that
any two situations give rise to two non-intersecting (except in (0, 0) and
(1, 1)) Lorenz curves. This means that, for two situations, if one
fractional impact factor is larger than the other one, the same is true for
all the other fractional impact factors. We show, by counterexample that
this is not so for "classical" impact factors, where one goes back to fixed
time periods.

The paper also presents methods to determine the rates c and g from
practical data and examples are given. (c) 2005 Elsevier Ltd. All rights
reserved.

Addresses: Egghe L (reprint author), Limburgs Univ Ctr, Univ Campus,
Diepenbeek, B-3590 Belgium
Limburgs Univ Ctr, Diepenbeek, B-3590 Belgium
Univ Antwerp, Antwerp, B-2610 Belgium

E-mail Addresses: leo.egghe at luc.ac.be

Publisher: PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE,
KIDLINGTON, OXFORD OX5 1GB, ENGLAND
Subject Category: COMPUTER SCIENCE, INFORMATION SYSTEMS; INFORMATION
SCIENCE & LIBRARY SCIENCE
IDS Number: 956XE

ISSN: 0306-4573

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