Impact and Other Factors: What’s in a Number?

Lois Lehman-McKeeman

Editor

The journal impact factor is an index used to evaluate the relative quality and importance of a journal and is often used to compare journals in the same field. It is recognized as a measuring stick by which all journals are evaluated. For many scientists, it is an important consideration when determining where to submit manuscripts, and it is frequently used when evaluating the significance of a colleague’s work. It can also be a determining factor for institutional libraries when deciding what subscriptions are most important to carry.

The impact factor is defined as the frequency with which the "average article" is cited in a particular year. It is calculated by dividing the number of citations to articles published in the previous two years by the total number of articles published in the same two years. The most recent impact factor for Toxicological Sciences is the index for 2001 (thereby based on the citations during 1999 and 2000). The impact factor is 2.734, the highest value to date for the journal. This value places Toxicological Sciences in the top 10 of all toxicology-related journals. More precisely, the journal ranks 10th out of 78 journals. Given that the top three journals are dedicated to review articles, the impact factor for Toxicological Sciences is firmly in the top 10 percent of all toxicology journals.1

An important observation regarding the impact factor for Toxicological Sciences is that this value has increased steadily over the past 3 years. The value for 2001 represents a 54% increase over the factor in 1999. The annual increase reflects the progress the journal has made in adjusting its scope and focus to cover all aspects of toxicological research. Furthermore, the magnitude and rate of improvement in the impact factor distinguishes Toxicological Sciences from all other journals in this discipline.

Another important index of a journal’s impact measures how quickly the "average article" in a journal is cited. The immedacy index indicates how often published articles are cited within the same year. For 2001, the index for Toxicological Sciences was 0.507, ranking it 5th overall and ahead of several of the toxicology journals dedicated to review articles. This value also reflects the timeliness and relevance of articles published in the journal.

While these numerical indexes reflect positively on the journal, we need to also consider whether they accurately reflect the success of the journal in meeting its overall objectives. Toxicological Sciences is intended to be diverse in its scope and global in its outlook. How do you derive a number that measures that? As the official journal of the Society of Toxicology, Toxicological Sciences will be successful if it is considered to be indispensable to both toxicologists and scientists in other fields of biomedical and environmental research. So while the numbers are encouraging, we need to continue to emphasize the quality of the original research that we publish, we need to work to increase contributions to the journal from scientists whose work impacts toxicology, and we need to remain relevant to a diverse readership.

We can’t ignore the numbers. However, we will continue to work toward sustained improvement of the journal from submission to publication.

NOTES

1 Institute for Scientific Information; http://www.isinet.com/webofknowledge. Back





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