CWTS Leiden Ranking 2015

David Wojick dwojick at CRAIGELLACHIE.US
Wed May 20 17:23:07 EDT 2015

Dear Nees Jan,

How do you apply 4000 field categories to individual papers? A semantic 
algorithm? Is this explained on the website? It sounds very difficult.

Also if the categories are not visible how is the methodology transparent?

My best wishes,


At 04:06 PM 5/20/2015, you wrote:
>Adminstrative info for SIGMETRICS (for example unsubscribe): 
>Dear Loet,
>Yes, your understanding is correct. MNCS, TNCS, PP(top 10%), P(top 10%), 
>and the other field-normalized impact indicators all use the 4000 fields 
>for the purpose of normalization. The Web of Science subject categories 
>are not used.
>Unfortunately, the 4000 fields are not visible. Because these fields are 
>defined at the level of individual publications rather than at the journal 
>level, there is no easy way to make the fields visible. This is something 
>that hopefully can be improved in the future.
>We have decided to move from 800 to 4000 fields because our analyses 
>indicate that with 800 fields there still is too much heterogeneity in 
>citation density within fields. A detailed analysis of the effect of 
>performing field normalization at different levels of aggregation is 
>reported in the following paper by Javier Ruiz-Castillo and Ludo Waltman: 
>In this paper, it is also shown that at the level of entire universities 
>field-normalized impact indicators are quite insensitive to the choice of 
>an aggregation level.
>Best regards,
>Nees Jan
>From: ASIS&T Special Interest Group on Metrics 
>[mailto:SIGMETRICS at LISTSERV.UTK.EDU] On Behalf Of Loet Leydesdorff
>Sent: Wednesday, May 20, 2015 9:28 PM
>Subject: Re: [SIGMETRICS] CWTS Leiden Ranking 2015
>Adminstrative info for SIGMETRICS (for example unsubscribe): 
>Dear Nees Jan,
>As always impressive! Thank you.
>Are the approximately 4,000 fields also visible in one way or another? Do 
>I correctly understand that MNCS is defined in relation to these 4,000 
>fields and not to the 251 WCs? Is there a concordance table between the 
>fields and WCs as there is between WCs and five broad fields in the Excel 
>I think that I understand from your and Ludo’s previous publications how 
>the 4,000 fields are generated. Why are there 4,000 such fields in 2015, 
>and 800+ in 2014? Isn’t it amazing that trends can despite the 
>discontinuities be smooth? Or are indicators robust across these scales?
>Best wishes,
>Loet Leydesdorff
>Emeritus University of Amsterdam
>Amsterdam School of Communication Research (ASCoR)
><mailto:loet at>loet at ; 
>Honorary Professor, <>SPRU, University of 
>Guest Professor <>Zhejiang Univ., Hangzhou; 
>Visiting Professor, <>ISTIC, Beijing;
>Visiting Professor, <>Birkbeck, University of London;
>From: ASIS&T Special Interest Group on Metrics 
>On Behalf Of Eck, N.J.P. van
>Sent: Wednesday, May 20, 2015 8:27 PM
>Subject: [SIGMETRICS] CWTS Leiden Ranking 2015
>Adminstrative info for SIGMETRICS (for example unsubscribe): 
>Release of the CWTS Leiden Ranking 2015
>Today CWTS has released the 2015 edition of the Leiden Ranking. The CWTS 
>Leiden Ranking 2015 offers key insights into the scientific performance of 
>750 major universities worldwide. A sophisticated set of bibliometric 
>indicators provides statistics on the scientific impact of universities 
>and on universities’ involvement in scientific collaboration. The CWTS 
>Leiden Ranking 2015 is based on Web of Science indexed publications from 
>the period 2010–2013.
>Improvements and new features in the 2015 edition
>Compared with the 2014 edition of the Leiden Ranking, the 2015 edition 
>includes a number of enhancements. First of all, the 2015 edition offers 
>the possibility to perform trend analyses. Bibliometric statistics are 
>available not only for the period 2010–2013 but also for earlier periods. 
>Second, the 2015 edition of the Leiden Ranking provides new impact 
>indicators based on counting publications that belong to the top 1% or top 
>50% of their field. And third, improvements have been made to the 
>presentation of the ranking. Size-dependent indicators are presented in a 
>more prominent way, and it is possible to obtain a convenient one-page 
>overview of all bibliometric statistics for a particular university.
>Differences with other university rankings
>Compared with other university rankings, the Leiden Ranking offers more 
>advanced indicators of scientific impact and collaboration and uses a more 
>transparent methodology. The Leiden Ranking does not rely on highly 
>subjective data obtained from reputational surveys or on data provided by 
>universities themselves. Also, the Leiden Ranking refrains from 
>aggregating different dimensions of university performance into a single 
>overall indicator.
>The Leiden Ranking is available at 
>Nees Jan van Eck PhD
>Head of ICT
>Centre for Science and Technology Studies
>Leiden University
>P.O. Box 905
>2300 AX Leiden
>The Netherlands
>Willem Einthoven Building, Room B5-35
>Tel: +31 (0)71 527 6445
>Fax: +31 (0)71 527 3911
>E-mail: <mailto:ecknjpvan at>ecknjpvan at
>Homepage: <>
>VOSviewer: <>
>CitNetExplorer: <>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the SIGMETRICS mailing list