Stuart Sheiber recently gave a talk at Caltech, which prompted the following blogospheric exchange with Stevan Harnad (which I recommend highly if you are interested in Green vs Gold OA and the intricacies of OA mandate politics):

Harnad --> Sheiber --> Harnad

followed by this related post on "proportion and strategy" from Prof Harnad, the main points of which he also left as a comment on a couple of my posts:

#1: The vast majority of current (peer-reviewed) journal articles are not OA (Open Access) (neither Green OA nor Gold OA ).
#2: The vast majority of journals are not Gold OA.
#3: The vast majority of journals are Green OA.
#4: The vast majority of citations are to the top minority of articles (the Pareto/Seglen 90/10 rule).
#5: The vast majority of journals (or journal articles) are not among the top minority of journals (or journal articles).
#6: The vast majority of the top journals are not Gold OA.
#7: The vast majority of the top journals are Green OA.
#8: The vast majority of article authors would comply willingly with a Green OA mandate from their institutions and/or funders.
#9: The vast majority of institutions and funders do not yet mandate Green OA.
#10: The vast majority of Gold OA journals are not paid-publication journals.
#11: The vast majority of the top Gold OA journals are paid-publication journals.
#12: The vast majority of institutions do not have the funds to subscribe to all the journals their users need.

CONCLUSION I: The fact that the vast majority of Gold OA journals are not paid-publication journals is not relevant if we are concerned about providing OA to the articles in the top journals.

CONCLUSION II: Green OA, mandated by institutions and funders, is the vastly underutilized means of providing OA.

CONCLUSION III: It is vastly more productive (of OA) for universities and funders to mandate Green OA than to fund Gold OA.

I think there is a considerable strategic error embedded in those premises and the conclusions which follow, the basis of which is the emphasis on "the top minority of journals (or journal articles)". The 90/10 rule is not relevant: the goal of OA is 100% OA, not 10% -- not even "the top" 10% in which is concentrated 90% of whatever your metrics are measuring.

Much of the potential of OA lies in the provision of a comprehensive corpus of information on which to build the semantic web. Comprehensivity matters, because just as re-use beyond the scope of the original author's imagination is a primary impetus for information sharing between humans, it is folly to imagine that we can determine ahead of time what will matter to machines -- that is, which articles will be crucial to finding new and unexpected connections in text- and data-mining initiatives. The more complete the corpus, the more likely we can refine from it insights that are currently unpredictable.

Also, in an odd bit of circularity, 100% OA is vital to the development of rich, fine-grained, multiply cross-validated metrics that will likely be more reliable than existing metrics in guiding management decisions and researcher information searches. If we focus on "the top" journals and articles, we hamstring our best strategy for improving the methods with which we identify quality in the first place.

It's also worth addressing claim #11 separately. For the direct argument against the assertion that most of the "top" Gold OA journals charge fees, see Peter Suber:

If this is a claim about quality, or about future submission patterns, as opposed to present submission patterns, then it's an assumption for which there is no evidence.  Nobody has done the studies. [...] In the absence of studies, this is all we know:

[T]here are strong and weak OA journals, just as there are strong and weak TA journals. Hence, any analysis focusing on weak OA journals and strong TA journals (as if to show the superiority of TA journals) would be as arbitrary as one focusing on weak TA journals and strong OA journals (as if to show the superiority of OA journals). Without some additional argument showing that the journals on which they focus are typical of their breeds, they would be guilty of cherry-picking and generalizing from an unrepresentative sample.

There is, however, a neglected and (in my opinion) important counter-argument: even if that assertion is true, it is surely equally or more the case that the vast majority of toll-access journals charge author-side fees in addition to subscription charges. A 2005 Kaufman-Wills study found that 75% of TA journals in their sample charged author-side fees. There is at least as much reason to suppose that the top-ranked TA journals are to be found among the fee-charging cohort as there is to suppose the same of OA journals.

The NIH estimates that it pays author-side fees to the tune of $100 million per year, and funds the publication of some 80,000 scholarly articles. Assuming, in order to be conservative, 5% Gold OA at fees that are triple the average TA fee, that averages out to $1136/article, but what's sauce for the TA goose is sauce for the OA gander: if the Kaufman-Wills figures are broadly representative then those TA journals that charge additional author-side fees are charging, on average, $1515 per article. That's more than PLoS ONE, more than most BMC journals and more than any Hindawi journal.

It follows that, since we are not -- that is, I argue that we should not be -- "concerned about providing OA to the articles in the top journals", the fact that most Gold OA journals do not charge fees is in fact relevant to all strategies for increasing OA to the research literature.

I think I disagree with the second conclusion also -- in the most comprehensive study so far, about 8% of articles published in 2006 were available via Gold OA, whereas a further 11% was available as a self-archived copy. I agree, of course, that both are vastly underutilized relative to the goal of 100% OA, but it doesn't seem to me that Green suffers more neglect than Gold.

Given the flaws in some premises and the first two conclusions, I don't believe that conclusion 3 stands up either. I find Stuart Sheiber's argument for the Harvard model compelling:

In summary, a university that commits to the open access compact¹ will more easily be able to answer objections against green OA policies specifically because it has an approach to long-range support for gold OA publishing, not in spite of it. The two models are inextricably tied. I, like Professor Harnad, am interested in facilitating the adoption of green OA policies. I proposed the open access compact in large part because I expect that adoption of the compact will lead to more green OA policies. The open access compact is therefore contributory to the promotion of green OA, not a sidetrack to it. I of course encourage universities to adopt green OA policies before gold OA support, but given that dystopian fears of faculty are preventing adoption of such policies, an open access compact that might assuage these worries should not be delayed.

¹ The compact simply states that ""The university commits to underwrite reasonable article processing fees for open-access journals for which funds are not otherwise available".

Given all of the above, the optimal strategy seems to me to be the one adopted by Harvard: a Green OA mandate and careful (fiscally responsible) support for Gold OA.