New Letter to the Editor

Loet Leydesdorff loet at LEYDESDORFF.NET
Sun Mar 29 10:17:00 EDT 2015

Dear Lutz, 


This letter is remarkable because you plead for using the Mean Normalized Citation Score MNCS. But: 


1.      Why should one use the mean of a highly skewed distribution? In other papers, you argued in favour of using percentile rank classes. At least, one could use the top-10% or the median as a non-parametric alternative.

2.      It is far from clear how one should normalize. Normalization presumes reference sets. One often use Web-of-Science Subject Categories for this, but these have been shown to be sometimes very heterogeneous, and in other cases overlapping. I would not advise to use them for evaluation purposes because one may end up with a lot of error.


The Leiden Rankings 2014 are for these reasons (among others) no longer based on MNCS (as they were in 2013). You argue that these are de-facto standards, but why should one continue to use de-facto standards that are not valid?








Bornmann, L., & Mutz, R. (2011). Further steps towards an ideal method of measuring citation performance: The avoidance of citation (ratio) averages in field-normalization. Journal of Informetrics, 5(1), 228-230.


Loet Leydesdorff and Lutz Bornmann, The Operationalization of  <> "Fields" as WoS Subject Categories (WCs) in Evaluative Bibliometrics: The cases of "Library and Information Science" and "Science & Technology Studies", Journal of the Association for Information Science and Technology (in press); doi: 10.1002/asi.23408 <> 





Loet Leydesdorff 

Emeritus University of Amsterdam
Amsterdam School of Communications Research (ASCoR)

 <mailto:loet at> loet at ;  <> 
Honorary Professor,  <> SPRU, University of Sussex; 

Guest Professor  <> Zhejiang Univ., Hangzhou; Visiting Professor,  <> ISTIC, Beijing;

Visiting Professor,  <> Birkbeck, University of London; 



From: ASIS&T Special Interest Group on Metrics [mailto:SIGMETRICS at LISTSERV.UTK.EDU] On Behalf Of Bornmann, Lutz
Sent: Sunday, March 29, 2015 3:22 PM
Subject: [SIGMETRICS] New Letter to the Editor



Bornmann, L. (in press). Nature’s top 100 revisited. Journal of the Association for Information Science and Technology


Recently, Van Noorden, Maher, and Nuzzo (2014) published a list of papers which are among the 100 most highly cited papers of all time. This letter argues that such a list should not be produced on the base of bare citation counts, but normalized bibliometric indicators – the standard in bibliometrics.




Dr. Dr. habil. Lutz Bornmann

Division for Science and Innovation Studies

Administrative Headquarters of the Max Planck Society

Hofgartenstr. 8

80539 Munich

Tel.: +49 89 2108 1265

Mobil: +49 170 9183667

Email: bornmann at

WWW:  <>

ResearcherID:  <>

ResearchGate:  <>


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