Ramanana-Rahary, S et al Aggregation properties of relative impact and other classical indicators: Convexity issues and the Yule-Simpson paradox PROC OF ISSI 2007: 11TH INTL CONF OF THE ISSI, VOLS I AND II 643-654, 2007

[Eugene Garfield]

Email address: suzy.ramanana at obs-ost.fr

Author(s): Ramanana-Rahary, S (Ramanana-Rahary, Suzy); Zitt, M (Zitt, 
Michel); Rousseau, R (Rousseau, Ronald) 

Title: Aggregation properties of relative impact and other classical 
indicators: Convexity issues and the Yule-Simpson paradox 

Editor(s): TorresSalinas, D; Moed, HF 

Source: PROCEEDINGS OF ISSI 2007: 11TH INTERNATIONAL CONFERENCE OF THE 
INTERNATIONAL SOCIETY FOR SCIENTOMETRICS AND INFORMETRICS, VOLS I AND II 
643-654, 2007 

Language: English 
Document Type: Article
 
Conference Title: 11th International Conference of the International-
Society-for-Scientrometrics-and-Informetrics 

Conference Date: JUN 25-27, 2007 

Conference Location: Madrid, SPAIN 

Conference Sponsors: Int Soc Scientrometr & Informetr, CSIC, Minist Educ & 
Ciencia, FECYT, Comunidad Madrid, Eugene Garfield Fdn, Thomson Sci, 
Elsevier, Journal Informetr, Scopus, Ayuntamiento Madrid, Sci Metrix, Univ 
Carlos III Madrid 

Author Keywords: Yule-Simpson paradox; convexity; impact measures; 
research evaluation 

KeyWords Plus: INTERNATIONAL SCIENTIFIC COLLABORATION; CITATION; SCIENCE 

Abstract: Among classical bibliometric indicators, direct and relative 
impact measures for countries or other players in science are appealing 
and standard. Yet, as shown in this article, they may exhibit undesirable 
statistical properties, or at least ones that pose questions of 
interpretation in evaluation and benchmarking contexts. In this article, 
we address two such properties namely sensitivity to the Yule-Simpson 
effect, and a problem related to convexity. The Yule-Simpson effect can 
occur for direct impacts and, in a variant form, for relative impact, 
causing an apparent incoherence between field values and the aggregate 
(all-fields) value. For relative impacts, it may result in a severe form 
of 'out-range' of aggregate values, where a player's relative impact 
shifts from 'good' to 'bad', or conversely. Out-range and lack of 
convexity in general are typical of relative impact indicators. Using 
empirical data, we suggest that, for relative impact measures, 'out-range' 
due to lack of convexity is not exceptional. The Yule-Simpson effect is 
less frequent, and especially occurs for small players with particular 
specialisation profiles. 

Addresses: Observ Sci & Tech OST, Paris, France. 

Publisher Name: INT SOC SCIENTOMETRICS & INFORMETRICS-ISSI 
Publisher Address: KATHOLIEKE UNIV LEUVEN, FACULTEIT E T E W, DEKENSTRAAT 
2, LEUVEN, B-3000, BELGIUM 

Cited Reference Count: 19 

BALASSA B
Trade Liberalization and 'Revealed' Comparative Advantage
MANCHESTER SCH EC SO 33 : 99 1965   

 BRAUN T
SCIENTOMETRIC INDICA : 1985   

 BRUSONI S
HDB QUANTITATIVE SCI : 2004   

 DAVID HA
ANNOTATED READINGS H : 137 2001 
  
 EGGHE L
A general framework for relative impact indicators
CAN J INFORM LIB SCI 27 : 29 2002
   
 GARFIELD E
J LIBRARY HISTORY 2 : 235 1967 
  
 GARFIELD E
Random thoughts on citationology. Its theory and practice - Comments on 
theories of citation?
SCIENTOMETRICS 43 : 69 1998  
 
 GLANZEL W
Modelling and measuring multilateral co-authorship in international 
scientific collaboration. Part II. A comparative study on the extent and 
change of international scientific collaboration links
SCIENTOMETRICS 40 : 605 1997  
 
 GRUPP H
FDN EC INNOVATIONS T : 1998   

 LUUKKONEN T
The measurement of international scientific collaboration
SCIENTOMETRICS 28 : 15 1993 
  
 MAY RM
The scientific wealth of nations
SCIENCE 275 : 793 1997  
 
 MURUGESAN P
Variation of the nature of citation measures with journal and scientific 
specialties
J AM SOC INFORM SCI 29 : 141 1978   

 SCHUBERT A
Relative indicators and relational charts for comparative assessment of 
publication output and citation impact
SCIENTOMETRICS 9 : 281 1986   

 TIJSEEN RJW
Quasi-correspondence analysis in scientometric transaction matrices
SCIENTOMETRICS 11 : 351 1987  
 
 VANRAAN AFJ
HDB QUANTITATIVE SCI : 19 2004   

 VINKLER P
Relations of relative scientometric indicators
SCIENTOMETRICS 58 : 687 2003   

 ZITT M
Relativity of citation performance and excellence measures: From cross-
field to cross-scale effects of field normalisation
SCIENTOMETRICS 63 : 373 2005  
 
 ZITT M
Correcting glasses help fair comparisons in international science 
landscape: Country indicators as a function of ISI database delineation
SCIENTOMETRICS 56 : 259 2003  
 
 ZITT M
Shadows of the past in international cooperation: Collaboration profiles 
of the top five producers of science.
SCIENTOMETRICS 47 : 627 2000