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Caveats for the journal and field normalizations in the CWTS ("Leiden")
evaluations of research performance, Journal of Informetrics (forthcoming);

	Abstract: The Center for Science and Technology Studies at Leiden
University advocates the use of specific normalizations for assessing
research performance with reference to a world average. The Journal Citation
Score (JCS) and Field Citation Score (FCS) are averaged for the research
group or individual researcher under study, and then these values are used
as denominators of the (mean) Citations per publication (CPP). Thus, this
normalization is based on dividing two averages. This procedure only
generates a legitimate indicator in the case of underlying normal
distributions. Given the skewed distributions under study, one should
average the observed versus expected values which are to be divided first
for each publication. We show the effects of the Leiden normalization for a
recent evaluation where we happened to have access to the underlying data. 

Tobias Opthof [1,2], Loet Leydesdorff [3]

[1] Experimental Cardiology Group, Heart Failure Research Center, Academic
Medical Center AMC, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. 

[2] Department of Medical Physiology, University Medical Center Utrecht,
Utrecht, The Netherlands.

[3] Amsterdam School of Communications Research (ASCoR), University of
Amsterdam, Kloveniersburgwal 48, 1012 CX Amsterdam, The Netherlands. 


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