A slight sense of despondency overcame me when I saw in a number of recent posts on various discussion fora about open access, that the fallacy of the number of journals being a measure of size (of activity or the amount of article published in a certain area) is alive and well. The fallacious argument is used by members of the pro-open-access camp as well those from anti-open-access circles. The pros are saying “look how many open access journals there are!” and the antis “look how few open access journals!”, either of them proving or disproving exactly nothing.
The number of articles different journals publish in a given period of time can vary by an enormous amount – a factor of 100 is relatively common. There are plenty of journals that publish 20 or fewer articles a year, and quite a number that publish 2000 or more.
Even if journals were more uniform in size, counting open access journals to establish how much peer-reviewed material is available with open access is flawed. It is with very good reason that the Bethesda Statement says “Open access is a property of individual works, not necessarily journals or publishers.” Some BioMed Central journals have non-open-access articles and an increasing number of journals will publish open access material (e.g. Springer’s 1250 odd titles and a growing selection of OUP's and Blackwell’s titles, among others).
Number of articles is a better measure than numbers of journals, but what seems more important to me is the number of opportunities that authors have to publish with open access. They have grown dramatically over the last year.