The new Impact Factors 2008 were just released by Thomson Reuters (2008 Journal Citation Reports). We are delighted to announce that Molecular Systems Biology continues its progression, with an Impact Factor 2008 of 12.243.

We address a warm thank you to all our authors and reviewers for this wonderful success, which reflects the current extraordinary dynamism and enthusiasm in the fields of systems biology, synthetic biology and systems medicine!

The limitations of the Impact Factors (IF) have been largely discussed. In particular, it might be questionable to use IFs to rank journals with highly variable scopes, audiences and citation patterns. Moreover, article-centered metrics (such as individual citations, number of download, highlights in N&V, etc...) might be more appropriate to evaluate the contributions of individual researchers, rather than solely relying on the proxy provided by journal-based citation indexes. Nevertheless, when considering the variation of IF over time for a given journal, the impact of some of the confounding factors mentioned above might be reduced, at least to some extent. To facilitate exploration of the progression of IFs over the last five years, I include at the end of this post a Google Motion Chart to visualize IFs of a (rather subjective) selection of journals related to the fields of molecular and cell biology.

One observation that becomes apparent when toying around with this visualization, is that relatively few journals–in this selection!–see their IF raising over a period of 5 years, whereas many seem to be subject to a progressive erosion. This is also visible if one clusters the normalized time profiles, showing that the downward profile (in red) is frequent, at least within the selection used for the Motion Chart below (each curve is the cluster's center with a thickness proportional to the number of journals in this cluster):

Why is that? It is hard to know. Perhaps, it might reflect some global effects affecting many journals at the same time: proliferation of new journals, changes in the pattern of citations directed to reviews rather than primary research, shift to citations of medically and clinically-oriented journals to highlight the medical relevance of the citing paper, etc... On the more positive side, those journals with upward progression (green curve above) may provide pointers to particularly dynamic fields.

In any case, given the above global trends, we are even more happy to open a bottle of Champagne to celebrate and enjoy the moment... :-)

For an easy start with the exploration of the data, select 'Impact Factor' for the Y axis, 'Time' for the X axis, color by 'up vs down', 'same size' in the 'size' menu, check a few of your favorite journals (don't forget to click on Mol Syst Biol!) and check the 'Trail' box. Press the 'play' button to start the animation. Interesting visualizations are also possible with the bar chart option (Click on second tab on top). See also instructions on the relevant Google Docs help page. Have fun!
Legend:

• 'IF': impact factor
• 'IF-IF2004': the Impact Factor 2004 (or the first available) was subtracted from all the other, to facilitate visualization of the progression
• 'up vs do': +1 if IF2008>IF2004, -1 otherwise
• 'cluster #' & 'profile type': 0=undefined because missing values, 1=profiles goes up then down, 2=down then up, 3=down, 4=up