Open access publisher BioMed Central, US, has announced that the 2007 edition of the Thomson Reuters Journal Citation Reports will include the first official Impact Factors for 12 BioMed Central journals as well as updated Impact Factors for 28 more. The reports will be released later this week.
As BioMed Central has previously noted, delays in "tracking" journals by Thomson Reuters mean that Impact Factors are often not made available as soon as they could be. Even when several years of citation data exists in the Web of Science "cited reference" database, the timing of publication of an Impact Factor in the Journal Citation Reports depends on when the journal was selected for tracking. The availability of an alternative set of journal citation metrics, the SCImago journal rankings, based on Scopus data, has again called attention to this problem.
For instance, three of the four most highly cited journals at the top of SCImago's Nutrition and Dietetics category are open access journals from BioMed Central (International Journal of Behavioral Nutrition and Physical Activity, Nutrition & Metabolism and Nutrition Journal). However, due to the timing of the tracking decisions made by Thomson Reuters, these journals will not receive official Impact Factors until June 2009, 2010 and 2011 respectively.
However, the Thomson Reuters citation data does make it possible to calculate unofficial Impact Factors for BioMed Central journals - even those that are not yet listed in the JCR. For this, the same formula is used as for the official Impact Factor calculation. Thomson Reuters has now calculated the 2007 unofficial Impact Factors for nearly 100 BioMed Central journals.
