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Re: Does the arXiv lead to higher citations and reduced publisher downloads?

On Tue, 14 Mar 2006, Phil Davis wrote:

> Liblicense, While our study confirms the same citation 
> advantage reported by others, it does not attribute Open Access 
> as the cause of more citations, but to Self-Selection. Open 
> Access therefore may be a result, not a cause, of authors 
> promoting higher-quality work.
> Does the arXiv lead to higher citations and reduced publisher downloads for
> mathematics articles?
> Authors: Philip M. Davis, Michael J. Fromerth
> Date: March 14, 2006
> http://arxiv.org/abs/cs.DL/0603056

The full text of Phil Davis's paper is not yet accessible, so I 
can only respond to the abstract.

There are many plausible components of the OA advantage, of which 
self-selection (Quality Bias: QB) is certainly one -- but not the 
only one, and unlikely to be the principle one, except under a 
few special conditions. QB is a temporary phenomenon, obviously, 
disappearing completely at 100% OA. Same is true for the 
Competitive Advantage (CA) of (comparable) OA papers over non-OA 
papers in the same journal issue, as well as the Arxiv Advantage 
(the advantage of appearing jointly in a central, widely 
consulted repository).

Once 100% OA is reached, QB, CA and AA all vanish. (AA vanishes 
because of OAI interoperability and central harvesting services.)

But there are three other components that remain even at 100% OA:

Early Access Advantage (EA): The permanent citation boost from earlier access
Quality Advantage (QA): The permanent advantage of quality once the
     playing field has been levelled and affordability/accessibility no
     longer biases what is and is not accessible
Usage Advantage (UA): Average downloads for OA articles are at least
     double those of non-OA articles

     OA Impact Advantage = EA + (AA) + (QB) + QA + (CA) + UA

> An analysis of 2,765 articles published in four math journals 
> from 1997-2005 indicated that articles deposited in the arXiv 
> received 35% more citations on average than non-deposited 
> articles (an advantage of about 1.1 citations per article), and 
> this difference was most pronounced for highly-cited articles. 
> The most plausible explanation was not the Open Access or Early 
> View postulates, but Self-Selection, which has led to higher 
> quality articles being deposited in the arXiv.

Without seeing the full text one cannot be sure of how this was 
ascertained, but let us assume that it was by correlation 
(looking at the author's track record, and their comparable 
non-OA articles, to show that there is a strong correlation 
between prior author/article citation rates and probability of 
later self-archiving).

There is no doubt at all that this is a causal factor, and indeed 
it is the example set by the high-quality authors that helps 
encourage other authors to self-archive.

But the only systematic way to show that QB is the *only* 
component of the OA advantage, or the biggest one, is to test it 
at all levels of self-archiving, from 1% to 99%. Obviously a 
citation advantage that persists even as a larger and larger 
proportion of the research in the field becomes OA is less and 
less likely to be due to the fact that the best author/articles 
are the ones being self-archived.

And it also has to be tested for articles at all citation levels 
(i.e., for comparable low, medium, and high-citation articles). 
The OA advantage is bigger at the higher citation levels, to be 
sure, but if it is even present at the lower ones, that already 
shows that QB is unlikely to be the only factor.

As to estimating the relative size of the causal contributions of 
each of the 6 factors -- this will require a more fine-grained 
analysis, taking into account not only %OA, citation level, and 
article age, but also article deposit date. Equating average 
citation levels for the authors and for the specialty domain will 
be necessary in the comparisons, and a lot of journals will need 
to be sampled, in diverse fields, to make sure patterns are not 

> Yet in spite of their citation advantage, arXiv-deposited 
> articles received 23% fewer downloads from the publisher's 
> website (about 10 fewer downloads per article) in all but the 
> most recent two years after publication. The data suggest that 
> arXiv and the publisher's website may be fulfilling distinct 
> functional needs of the reader.

That sounds like the Arxiv Advantage (AA) expressed in the 
downloads (UA).

Apart from total citation counts and downloads, other interesting 
variables to look at (and compare for OA effects) include: 
citation latency, citation longevity and other temporal measures; 
same for downloads; also authority impact (similar to google's 
PageRank: citations by higher-cited citers count for more), 
inbreeding/outbreeding coefficients, co-citations, and semantic 

Stevan Harnad

Hajjem, C., Harnad, S. and Gingras, Y. (2005) Ten-Year
Cross-Disciplinary Comparison of the Growth of Open Access and How it
Increases Research Citation Impact. IEEE Data Engineering Bulletin 28(4)
pp. 39-47.