It is heartening to know that 50% of articles published in 2008 were freely accessible online in 2012. But when did they become accessible? It could have been at any time from the date of acceptance for publication to December 2012!
A = Access (can be, free or paid, open or restricted, immediate or delayed)
SA = Subscription Access (also called TA: toll access, to include subscription access, licensed access, and pay-to-view access).
OA = Open Access (immediate, permanent, Gratis or Libre)
Gratis OA = toll-free online access
Libre OA = toll-free online access plus certain re-use rights
DA = Delayed Access (free online access after a delay period or embargo
Green OA = OA provided by author self-archiving
Gold OA = OA provided by the publisher — sometimes, but not always, for a publication fee
Delayed Green = free online access provided by the author after a delay (instead of immediately upon publication, which would been Green OA)
Delayed Gold = free online access provided by the publisher after a delay (instead of immediately upon publication, which would been Gold OA)
The purpose of Open Access (OA) is to maximize the uptake, usage, applications and impact of research findings by making them accessible to all users online, rather than just to those users who have subscription access (SA).
There are two ways for authors to make access to their published findings free for all: Publish them in a journal that makes the articles free for all online (“Gold OA”). Or publish them in any journal at all, but also self-archive the final, peer-reviewed draft free for all online (“Green OA”).
But both the Green and the Gold paths to access can be taken immediately, or only after a delay of months or years.
If subscription access (SA) is not OA but restricted access, because it is restricted to subscribers only, then surely both delayed Green Access and delayed Gold Access are not OA either, because access is restricted during any delay period.
Some journals, for example, impose a 12-month embargo on Green self-archiving. And of those journals where the journal itself makes its own articles freely accessible, some journals only do so 12 months after publication or longer.
In many fields, the growth tip for accessing and building upon new findings is within the first year or even earlier. (See the figure from Gentil-Beccot 2009). With delays, potential research progress is slowed and reduced, some of it perhaps even permanently lost.
Hence 50% DA is certainly better than 25% DA — but until research has 100% OA, there’s really not that much to tipple about…
Harnad, S (2013) OA 2013: Tilting at the Tipping Point. Open Access Archivengelism 1022