Recently there has been huge growth in the number of articles displayed on the Web of Science (WoS), but it is unclear whether this is linked to a growth of science or simply additional coverage of already existing journals by the database provider. An analysis of the category of journals in the period of 2000-2008 shows that the number of basic journals covered by Web of Science (WoS) steadily decreased, whereas the number of new, recently established journals increased. A rising number of older journals is also covered. These developments imply a crescive number of articles, but a more significant effect is the enlargement of traditional, basic journals in terms of annual articles. All in all it becomes obvious that the data set is quite instable due to high fluctuation caused by the annual selection criteria, the impact factor. In any case, it is important to look at the structures at the level of specific fields in order to differentiate between "real" and "artificial" growth. Our findings suggest that even-though a growth of about 34 % can be measured in article numbers in the period of 2000-2008, 17 % of this growth stems from the inclusion of old journals that have been published for a longer time but were simply not included in the database so far

The role of conference proceedings for scientific communication varies among the different research fields. It is thus difficult to determine how to use them in bibliometric studies that cover all or at least a variety of the research fields without favouring or penalizing observation subjects that are specialized in fields that rely heavily on conference proceedings. Also, the coverage of conference proceedings in bibliometric databases is often unclear. Not only have there been reports of misclassification but also of insufficient coverage. In this study, the Web of Science is used to give an overview of coverage of conference proceedings as well as advantages and pitfalls of their usage in bibliometric analyses. In particular, the focus lies on different citation behaviour of and for conference proceedings and the implications for bibliometric indicators. This is complemented by an investigation of the development of coverage and publication behaviour in conference proceedings which is compared to those of journal publications. Finally, the importance but also drawbacks and opportunities of acknowledging conference proceedings publications for bibliometric studies are summarized

It has been widely discussed how individuals change the way they act and react in studies just because they are under observation. In this paper, we try to analyse how this so-called Hawthorne effect applies to researchers that are the subject of bibliometric investigations. This encompasses individual assessments as well as international performance comparisons. We test various bibliometric indicators for notable changes in the last decade from a world-wide perspective and deduce explanations for changes from the observations. We then concentrate on the behaviour of German authors in particular, to show national trends. The German publication behaviour is evaluated in regard to citation rates and collaborations in publications and size, publisher country and impact of the journals chosen for publication. We can conclude that authors adapt their publication behaviour to aim for journals that are more internationally known and have a US publisher. Also, a trend from more specialized journals to journals with a broader scope can be observed that raises the question whether the implicit penalization of specialized fields in the bibliometrics leads to undesired shifts in conducted research

This paper deals with the role of a journal's publisher country in determining the expected citation rates of the articles published in it. We analyze whether a paper has a higher citation rate when it is published in one of the large publisher nations, the U.S., U.K., or the Netherlands, compared to a hypothetical situation when the same paper is published in journals of different origin. This would constitute a "free lunch," which could be explained by a Matthew effect visible on the countrylevel, similar to the well-documented Matthew effect on the author-level. We first use a simulation model that highlights increasing citation returns to quality as the central key condition on which such a Matthew effect may emerge. Then we use an international bibliometric panel data set of forty-nine countries for the years 2000-2010 and show that such a "free lunch" implied by this Matthew effect can be observed for top journals from the U.S. and depending on the specification also from the U.K. and the Netherlands, while there is no effect for lower-ranked American journals and negative effects for lower-ranked British journals as well as those coming from the Netherlands.