This collection of articles not only cover some of the most significant initiatives on new metrics for journals and the articles they contain, but also illustrate the growing importance of metrics in the evaluation of the status and impact of scholarly publications. As guest editor I am especially thrilled to include contributions from three acknowledged experts in the field: Joan Bollen, Gregg Gordon, and Henk Moed.
A few important, common themes emerge from all the articles. First, there is huge diversity among scholars and the ways in which they use and cite scholarly publications: one size does not fit all in terms of the metrics that provide insights into the impact and value of scholarly publications. Second, there is currently an over-reliance on the citation-based Journal Impact Factor, which is now used for purposes for which it was never intended. Third, there is now a real potential to develop a range of other citation- and usage-based metrics that will provide new insights into scientific publications and which will complement Journal Impact Factors.
Gregg Gordon, from a Social Sciences and Humanities (SSH) perspective, points out that there are significant differences between different fields of scholarship and argues that SSH requires a more varied set of metrics than do STM publications. He also picks up one theme that echoes through other articles in this collection: that there is currently an over-reliance on the citation-based Journal Impact Factor, which is open to abuse. Instead, he urges the adoption of a wider suite of article-based metrics that cover usage as well as citations.
In his article Henk Moed, of Elsevier Science, explains why the Impact Factor is an inadequate measure of the impact and value of journals and describes SNIP (Source Normalized Impact per Paper), the new citation-based measure of the impact of a scholarly journal that Elsevier has developed.
Johan Bollen has led the MESUR project for the last four years. During that time MESUR has pioneered the large-scale aggregation and normalization of usage data, defined minimal formatting and field requirements for article-level usage data, defined novel impact metrics, and created large-scale maps of science that can visualize current trends in science.
The article I have co-written with Paul Needham of Cranfield University provides an update on PIRUS2, the JISC-funded project whose aim is to develop a global standard for measuring usage at the individual article level, which can be implemented by repositories as well as publishers.
This collection of articles not only demonstrates the need for a wider range of metrics which are both usage- and citation-based to help us assess the impact of journals and the articles they contain, but it also shows the real progress which has been made in the development of such metrics.
Peter Shepherd has been Director of COUNTER since 2002. In this role he has not only been responsible for the day-to-day management of COUNTER, but has also participated in a number of wider industry initiatives to improve the quality and extend the coverage of online usage statistics.