[GOAL] Puzzled - please help

[Sally Morris]

Can anyone shed light on the following apparent discrepancy:
 
Laakso and Bjork (http://www.biomedcentral.com/1741-7015/10/124)  give a
figure for articles published in 2011 and indexed in Scopus - 11% in full
Gold journals, 0.7% in hybrid journals, and 5% in 'delayed OA' journals with
a delay of no more than 12 months [Stevan may not like the term, but I think
the rest of us understand it well enough, so let's not get into that!]
 
Gargouri et al (http://arxiv.org/ftp/arxiv/papers/1206/1206.3664.pdf), on
the other hand, give a figure of just 1.2% articles published in 2010 via
Gold OA
 
Furthermore, Gargouri et al give the percentage of 2010 articles available
via Green OA as 21.9% (2008 articles 20.6%).  Bjork et al
(http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011273) had a
very different figure of 11.9% for articles published in 2008.
 
I can't get my head round the spectacular difference between the two sets of
figures - can someone please explain?  I can't believe that
inclusion/exclusion in Scopus can possibly account for it. Am I missing
something?
 
Thanks
 
Sally
 
 
Sally Morris
South House, The Street, Clapham, Worthing, West Sussex, UK  BN13 3UU
Tel:  +44 (0)1903 871286
Email:  sally at morris-assocs.demon.co.uk
 
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