Guestimating PLoS ONE impact factor (Update)

Abhishek Tiwari did some analysis on the number of citations that PLoS ONE is getting so far using Scopus database. We had a small discussion over the numbers on FriendFeed and I ended up looking at different set of values also from Scopus. I tried to predict the first Impact Factor for PLoS ONE that might be out sometime this year.

Before showing the numbers I will repeat again that I think the IFs of the journal where a paper is published is a very poor measure of a papers importance. Although it is probably a good measure of the relative value of a journal (within a given field) we should be striving to pick what we read based on the value of a paper instead of the journal.

The Impact Factors that will be published this year are calculated as the total number of citations from 2008 to papers published in 2006 and 2007, divided by the number of citable units in 2006-2007 (articles and reviews). The data I am looking at is from Scopus so it varies a bit from the one in ISI. The variability comes from the decision of what to include as "citable" articles and from the journals that are covered in Scopus versus ISI.

One problem I found with Scopus data was that, for some journals, the database has multiple entries due to small variations in article titles. For PLoS Biology, PLoS Computational Biology and PLoS Genetics the number of articles published should be less than half of what is reported. This does not appear to be the case for PLoS ONE.
I downloaded the tables of published articles and tried to removed redundancies looking at the tittles and authors. I counted only articles and reviews as citable items but used all articles published in 2006-2007 to get the number of citations in the year 2008. I also did the same calculations for the impact factor of the previous year to be able to compare with the data from ISI. The results were comparable but not the same.



In summary, PLoS ONE might get an impact factor of about half of the expected for PLoS Computational Biology. The usual disclaimers should be said: I have no idea of how complete Scopus data is and how exactly it relates to ISI.

Update:

The official impact factor for PLoS ONE for 2008 is out and I is ~ 4.3. I underestimated it by 1.5. It is also amazing how many people search for this online. This post is my number one source of traffic to this blog. If you are reading this and typically sit in panels that decide on new faculty, please stop evaluating people by where they publish. This way, postdocs like me can focus on doing interesting science instead of trying to get into nature/cell/science.

Jonathan Eisen@PLoS

PLoS has a new Academic Editor in Chief that blogs, works on evolution and has been at SciFoo twice. Jonathan A. Eisen, explains his reasons for accepting the job in an editorial available online. Among other things, he states:

Second, I want to work with the professional staff at PLoS Biology, the Academic Editors, and anyone else in the community who shares my desire to build new initiatives that will keep PLoS Biology as a top-tier journal. These would include ideas like producing issues dedicated to particular themes, actively recruiting excellent papers in fields where OA is not yet common, producing more outreach and educational material, and engaging bloggers and fully embracing the Web 2.0 world.

I actually would like to get a bit more involved with what they are doing at PLoS, in particular with what they might be discussing for PLoS ONE and the hubs. Maybe I can pester them later on during the year. For some reactions on the news and more information, here is the related Postgenomic cluster.

I wonder if we will ever see the AEIC of Science/Nature/Cell blogging :). The editorials are the closest article format to a blog post but they insist on a somewhat exaggerated formality. Just as an example here is a link to the 2007 archives of the (great) editorials of Frank Gannon from EMBO reports.