585 research outputs found
Some modifications to the SNIP journal impact indicator
The SNIP (source normalized impact per paper) indicator is an indicator of
the citation impact of scientific journals. The indicator, introduced by Henk
Moed in 2010, is included in Elsevier's Scopus database. The SNIP indicator
uses a source normalized approach to correct for differences in citation
practices between scientific fields. The strength of this approach is that it
does not require a field classification system in which the boundaries of
fields are explicitly defined. In this paper, a number of modifications that
will be made to the SNIP indicator are explained, and the advantages of the
resulting revised SNIP indicator are pointed out. It is argued that the
original SNIP indicator has some counterintuitive properties, and it is shown
mathematically that the revised SNIP indicator does not have these properties.
Empirically, the differences between the original SNIP indicator and the
revised one turn out to be relatively small, although some systematic
differences can be observed. Relations with other source normalized indicators
proposed in the literature are discussed as well
Towards a new crown indicator: Some theoretical considerations
The crown indicator is a well-known bibliometric indicator of research
performance developed by our institute. The indicator aims to normalize
citation counts for differences among fields. We critically examine the
theoretical basis of the normalization mechanism applied in the crown
indicator. We also make a comparison with an alternative normalization
mechanism. The alternative mechanism turns out to have more satisfactory
properties than the mechanism applied in the crown indicator. In particular,
the alternative mechanism has a so-called consistency property. The mechanism
applied in the crown indicator lacks this important property. As a consequence
of our findings, we are currently moving towards a new crown indicator, which
relies on the alternative normalization mechanism
Rivals for the crown: Reply to Opthof and Leydesdorff
We reply to the criticism of Opthof and Leydesdorff [arXiv:1002.2769] on the
way in which our institute applies journal and field normalizations to citation
counts. We point out why we believe most of the criticism is unjustified, but
we also indicate where we think Opthof and Leydesdorff raise a valid point
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