We explore the possibility of using co-citation clusters over three time periods to track the emergence and growth of research
areas, and predict their near term change. Data sets are from three overlapping six-year periods: 1996-2001, 1997-2002 and
1998-2003. The methodologies of co-citation clustering, mapping, and string formation are reviewed, and a measure of cluster
currency is defined as the average age of highly cited papers relative to the year span of the data set. An association is
found between the currency variable in a prior period and the percentage change in cluster size and citation frequency in
the following period. The conflating factor of “single-issue clusters” is discussed and dealt with using a new metric called
Authors:Hariolf Grupp, Ulrich Schmoch, and Sybelle Hinze
Many international comparisons of the publication performance at themacro level are based on direct counts of citation frequencies
in the ScienceCitation Index. However, these comparisons may reveal a significant negativelanguage bias for non-English-speaking
countries, or other selection biases,which can be illustrated by the relation between research budgets of scientificinstitutions
and SCI publications. Against this background, a two-dimensionalrepresentation, specifying for the international alignment
of the nationalpublications and the journal-standardized citation impact, proves to be amore appropriate indicator base to
assess the citation performance of countriessuch as Germany. In the light of a ten countries' benchmark, time seriesof these
indicators for the nineties show a considerable impact of the Germanunification with a recent trend towards an adaptation
of publication behaviourin East Germany towards the Western patterns.
In order to quantify the influence of publication languages on the rate of citation of scientific articles, such East German journals from the Science Citation Index database were selected which publish relevant shares of contributions in several languages, especially in English and German. For a fixed period of time (1988) the selective citation impact of both English- and German-language articles was calculated. The results of our investigation reveal a non-uniform picture: In some cases English-language papers exhibit a significantly higher citations-per-paper average than German-language articles, but in a few cases German-language publications achieve a higher mean citation rate. For the half of selected journals there does not exist a statistically significant difference of citation frequencies of publications in both languages. Possible causes of these phenomena (editorial practice of journals, native countries of authors) are considered.
Summary In this study, journal impact factors play a central role. In addition to this important bibliometric indicator, which evolves around the average impact of a journal in a two-year timeframe, related aspects of journal impact measurement are studied. Aspects like the output volume, the percentage of publications not cited, and the citation frequency distribution within a set timeframe are researched, and put in perspective with the 'classical' journal Impact Factor. In this study it is shown that these aspects of journal impact measurement play a significant role, and are strongly inter-related. Especially the separation between journals on the basis of the differences in output volume seems to be relevant, as can be concluded from the different results in the analysis of journal impact factors, the degree of uncitedness, and the share of a journal its contents above or below the impact factor value.
It is the objective of this article to examine in which aspects journal usage data differ from citation data. This comparison
is conducted both at journal level and on a paper by paper basis. At journal level, we define a so-called usage impact factor
and a usage half-life in analogy to the corresponding Thomson’s citation indicators. The usage data were provided from Science
Direct, subject category “oncology”. Citation indicators were obtained from JCR, article citations were retrieved from SCI
and Scopus. Our study shows that downloads and citations have different obsolescence patterns. While the average cited half-life
was 5.6 years, we computed a mean usage half-life of 1.7 years for the year 2006. We identified a strong correlation between
the citation frequencies and the number of downloads for our journal sample. The relationship was lower when performing the
analysis on a paper by paper basis because of existing variances in the citation-download-ratio among articles. Also the correlation
between the usage impact factor and Thomson’s journal impact factor was “only” moderate because of different obsolescence
patterns between downloads and citations.
In reference to an exemplary bibliometric publication and citation analysis for a University Department of Psychology, some
general conceptual and methodological considerations on the evaluation of university departments and their scientists are
presented. Data refer to publication and citation-by-others analyses (PsycINFO, PSYNDEX, SSCI, and SCI) for 36 professorial
and non-professorial scientists from the tenure staff of the department under study, as well as confidential interviews on
self-and colleagues-perceptions with seven of the sample under study. The results point at (1) skewed (Pareto-) distributions
of all bibliometric variables demanding nonparametrical statistical analyses, (2) three personally identical outliers which
must be excluded from some statistical analyses, (3) rather low rank-order correlations of publication and citation frequencies
having approximately 15% common variance, (4) only weak interdependences of bibliometric variables with age, occupational
experience, gender, academic status, and engagement in basic versus applied research, (5) the empirical appropriateness and
utility of a normative typological model for the evaluation of scientists’ research productivity and impact, which is based
on cross-classifications with reference to the number of publications and the frequency of citations by other authors, and
(6) low interrater reliabilities and validity of ad hoc evaluations within the departments’ staff. Conclusions refer to the utility of bibliometric data for external peer reviewing
and for feedback within scientific departments, in order to make colleague-perceptions more reliable and valid.
Policy-makers in many countries emphasize the importance of non-publication output of university research. Increasingly, policies
are pursued that attempt to encourage entrepreneurial activity in universities and public research institutes. Apart from
generating spin-out companies, technology licensing, and collaborative research, attention is focused on patenting activities
of researchers. Some analysts suggest that there is a trade-off between scholarly publication and patenting activity. This
paper explores this relationship drawing on a data set of nanoscience publications and nanotechnology patents in three European
countries. In particular, this study examines whether researchers who both publish and patent are more productive and more
highly cited than their peers who concentrate on scholarly publication in communicating their research results. Furthermore,
this study investigates the collaborative activity of inventor-authors and their position in their respective networks of
scientific communication. The findings suggest that overall there seems to be no adverse relationship between publication
and patenting activity, at least not in this area of science and technology. Patenting scientists appear to outperform their
solely publishing, non-inventing peers in terms of publication counts and citation frequency. However, while they are considerably
over-represented in the top performance class, the data indicates that inventor-authors may not occupy top positions within
that group. An analysis of co-authorship links indicates that patenting authors can also play a prominent role within networks
of scientific communication. The network maps also point to groups where inventor-authors occur frequently and others where
this is not the case, which possibly reflects cognitive differences between sub-fields. Finally, the data indicates that inventor-authors
account only for a marginal share of publishing scholars while they play a substantial role amongst inventors.
The purpose of this study is to map semiconductor literature using journal co-citation analysis. The journal sample was gathered
from the INSPEC database from 1978 to 1997. In the co-citation analysis, the data compiled were counts of the number of times
two journal titles were jointly cited in later publications. It is assumed that the more two journals are cited together,
the closer the relationship between them. The journal set used was the 30 most productive journals in the field of semiconductors.
Counts of co-citations to the set of semiconductor journals were retrieved from SciSearch database, accessed through Dialog.
Cluster analysis and multi-dimensional scaling were employed to create two-dimensional maps of journal relationships in the
cross-citation networks. The following results were obtained through this co-citation study: The 30 journals fall fairly clearly
into three clusters. The major cluster of journals, containing 17 titles, is in the subject of physics. The second cluster,
consisting of 9 journals, includes journals primarily on material science. The remaining cluster represents research areas
in the discipline of electrical and electronic engineering. All co-cited journals share similar co-citation profiles, reflected
in high positive Pearson correlation. Two hundred and ninety-six pairs (68%) correlate at greater than 0.70. This shows that
there is strong relationship between semiconductor journals. Five individual journals in five paired sets with co-citation
frequency over 100,000 times include Physical Review B, Condensed Matter; Physical Review Letters; Applied Physics Letters; Journal of Applied Physics; and Solid State Communications.