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Vol. 23 No. 7 — Jul/Aug 2006

The papers were published in the Proceedings of the National Academy of Sciences (PNAS). In this hybrid journal (also known in OA circles as open choice), authors (or their funders) can pay $1,000 for immediate free access. In June 2004, PNAS became one of the first journals to make this option available to its authors.

Gunther Eysenbach, a health-policy specialist at the University of Toronto, is a self-described “moderate” advocate of OA publishing. He said, “I think in the future there will be a role for both business models, author-pays and reader-pays. I don’t evangelize.” Eysenbach also noted in an interview with Medscape Today that “unless you have a top paper that is publishable in one of the [five] major general medical journals—it is always better to publish in an OA journal than in a toll-access specialist journal.”

Potential Conflict of Interest

Eysenbach is also editor of the OA Journal of Medical Internet Research (JMIR). PLoS Biology senior editor Catriona MacCallum and managing editor Hemai Parthasarathy acknowledged the potential of a conflict of interest: “[W]e do have a strong and vested interest in publishing results that so obviously endorse our existence. Moreover, the author of the article is also an editor of an open-access journal. But sometimes a potential conflict of interest can actually help to ensure rigor.”

According to MacCallum and Par­tha­sarathy in a PLoS Biology editorial, “In this case, we have an acute interest in ensuring that the article meets the same, if not higher, standards as any other research article we publish. Not only must the conclusions provide a significant advance for the field, but the study must be technically sound, with appropriate evidence to support those conclusions.” They also note that, “As with all our research articles, we consulted through­out the evaluation process with an academic editor with appropriate expertise—in this case, Carol Tenopir, professor of information sciences at the University of Tennessee.”

Twice the Impact

Eysenbach monitored the number of times each of 1,500 papers was cited in later studies. “I chose an article-level approach,” he said, “comparing the bibliometric impact of a cohort of articles from the same journal (PNAS) that offers both an OA and a non-OA publishing option, adjusted for different article and author characteristics.”

He found that OA papers were twice as likely as other papers to be cited 4 to 10 months after publication. After 10 to 16 months, this citation rate rose to three times more likely to be cited. And in a supplementary editorial published on May 22 in JMIR, he provides additional data suggesting that the gap continues to widen in time. “While 36 of 212 (17.0 [percent]) of immediate journal OA articles were also self-archived, only 121 of 1,280 (10.6 [percent]) of non-OA papers on the journal site were self-archived (i.e., papers published originally as OA were more likely to be self-archived).”

According to Eysenbach, “The strength of the OA effect is particularly surprising because PNAS is a widely available journal that is accessible for most researchers through their library. In addition, articles are made freely available to nonsubscribers 6 months after publication.” He suggested, “The effect of OA publishing may be even higher in fields where journals are not widely available and where articles from the control group remain ‘toll-access.?”

Although other studies have examined the effect of OA on citation impact, the emphasis has been on self-archiving in institutional repositories. The OA journal studies noted that most of these journals are new, and comparisons between established journals can be problematic. Bibliometrics research is not simple to conduct and can be oversimplified in the hands of a novice. However, using an established journal such as PNAS provides a rigorous comparison.

The Open Choice Option

The study also demonstrates at least some author interest in the open choice model. Out of a total of 1,492 original articles, 212 (14.2 percent) were immediately published as OA. Authors of all articles came from 39 countries, with the majority of 65.8 percent coming from the U.S. Twelve countries constituted 95 percent of all the articles. Of those that were OA, Japan had the highest proportion (19.4 percent), followed by Israel (18.8 percent), Germany (15.7 percent), and then the U.S. (15.5 percent).

Stevan Harnad, longtime advocate of OA, responded by saying, “In fact, the only new knowledge from this small, journal-specific sample was (1) the welcome finding of how early the OA advantage can manifest itself, plus (2) some less clear findings about differences between first- and last-author OA practices, plus (3) a controversial finding that will most definitely need to be replicated on far larger samples in order to be credible: ‘The analysis revealed that self-archived articles are also cited less often than OA articles from the same journal.?”

It’s interesting to note that this report appeared in PloS Biology. After his study was published, the author stated in an editorial in JMIR that he questioned the financial sustainability of OA giants PLoS or BiomedCentral. “What is often forgotten is that these publishers are not the only open access publishers (they were not even the first open access publishers—with publishers like BMJ, Medscape, or JMIR being the true pioneers), and they are certainly not typical representatives,” he said. “The majority of open access journals operate using a lean publishing model, and many of them are financially sustainable.”