Do Open-Access Articles Have a Greater Research Impact?
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Do Open-Access Articles Have a Greater Research Impact? Kristin Antelman Although many authors believe that their work has a greater research impact if it is freely available, studies to demonstrate that impact are few. This study looks at articles in four disciplines at varying stages of adoption of open access—philosophy, political science, electrical and electronic engineering and mathematics—to see whether they have a greater im- pact as measured by citations in the ISI Web of Science database when their authors make them freely available on the Internet. The finding is that, across all four disciplines, freely available articles do have a greater research impact. Shedding light on this category of open access reveals that scholars in diverse disciplines are adopting open-access practices and being rewarded for it. here is currently an explosion ability of computer science conference of interest in the academic documents under the catchy title “Online and publishing communities or Invisible,” the notion that freely avail- about the promise—and pos- able papers have a greater research im- sible perils—of open-access scholarship pact has taken hold. (Lawrence’s preprint and publishing. Although the term “open itself was evidence of this phenomenon: access” is somewhat fluid, included under the version published in the journal Na- its banner are the so-called “two roads to ture [under a different title] was almost an open access”: open-access journals and a�erthought; more than seven hundred “e-print” (i.e., preprints or postprints) documents in Google reference “Online repositories, both of which make the full or Invisible.”2) Despite the limited do- text of scholarly articles freely available main of the Lawrence study, making it to everyone on the open Internet.1 Al- difficult to make assumptions about other though debate swirls around questions disciplines based on his findings, it is now of copyright, peer review, and publishing common to see the assertion that research costs, individual authors are taking action impact is increased by open access. For in this arena by posting their articles to example, Eugene Garfield casually noted personal or institutional Web pages and in a recent post to the American Scientist to disciplinary repositories. Open Access Forum listserv that “it has Since Steve Lawrence circulated his been demonstrated that on line access study of the impact of free online avail- improves both readership and citation Kristin Antelman is Associate Director for Information Technology at North Carolina State University Libraries; e-mail: [email protected]. 372 Do Open-Access Articles Have a Greater Research Impact? 373 impact.”3 Although this statement may A common author perspective is re- be intuitively believable, the evidence flected in a reported conversation with an to document it is still being collected. In electrophysiologist in the journal Science: addition to the Lawrence study, small “Free online papers are likely to reach studies of the research impact of e-prints more readers, he figures, and therefore have been done for physics, chemistry, attract more citations.”10 Backing this and a subdiscipline of computer sci- up is a survey of authors (primarily in ence.4–6 Preliminary results from a larger the life and medical sciences) sponsored study, which will look at articles from by the Joint Information Systems Com- seven thousand journals from the ISI Web mi�ee (JISC), which found that the two of Science database, indicate a significant principal reasons for publishing in an increased research impact for open-access open-access journal was belief in “the articles in physics.7 In related research, principle of free access for all readers,” a study performed using the Citebase followed by “I perceive OA journals to data found that the more o�en a paper have faster publication times.” The next is downloaded, the more likely it is to be two most important reasons were related cited (with the strongest correlation for to perception of research impact: “I per- high-citation papers and authors).8 ceive the readership to be larger” and “I In April 2004, ISI released a study titled think my article will be more frequently “The Impact of Open Access Journals,” in cited.”11 One quantifiable measure of au- which it compared impact factor and the thors’ belief that free access is valuable to number of citations of open-access journals them is their adoption of an open-access in the natural sciences with non-open-ac- option initiated by the Entomological cess journals. ISI found that “the OA jour- Society of America and now offered by nals have a broadly similar citation pa�ern a number of publishers. A�er offering to other journals, but may have a slight open access to individual articles for a tendency to earlier citations.”9 However, it (low) fee, they found that by the second qualifies the findings by noting that many year more than half of the authors elected of the journals in the study only recently to purchase it.12 shi�ed to open access, that high-profile ti- There also is more indirect evidence of tles (such as PLoS Biology) were too new to a link between free online availability and be included, and that their relatively small impact. Studies have shown that authors, sample included many regional titles that as consumers of research information, would not be expected to be high-impact rely heavily on browsing online journals journals. It also should be noted that this and articles.13 Brody and colleagues have study was of journals, not articles; it is open used data from the CiteSeer repository to to question whether these two groups of demonstrate that the “peak of citations journals are sufficiently comparable with occurs higher and sooner for papers one another in measures other than their deposited in each succeeding year.”14 access model to produce a meaningful Moreover, research has been done on the gauge of the impact of open access. Given tangential question of whether online that we are at an early stage in the evolu- journals receive greater use than journals tion of open-access journals, comparing available only in print. That research, un- the research impact of articles taken from dertaken at a point when only a portion the same issues of the same journals is a of journals were available in so-called more solid methodology for measuring the “combination” online and print editions, impact of open access. did not make the distinction between ac- 374 College & Research Libraries September 2004 cess to a licensed online version versus a on artifacts of scholarly communication freely available online version.15 (published articles). Two of Bormgan’s University libraries contemplating four bibliometric research question types providing support for open-access initia- are addressed, namely, characterizing tives, such as institutional repositories larger pa�erns of behavior in scholarly or open-access journals, face several key communities and evaluating measures of challenges. Librarians must be able to influence of scholarly contributions.16 draw on a sophisticated understanding This study does not attempt to ad- of the scholarly communication practices dress the variable of publisher policies of individual disciplines even as they are regarding posting of pre- or postprints of rapidly evolving, including scholars’ use articles from their journals, or the ques- of prepublication research material not tion of why authors choose to post or not traditionally part of the domain of librar- to post e-prints. ies in a print environment. If we choose to implement institutional repositories, Methodology we also must be able to persuade faculty, The four disciplines—mathematics, many of whom are for a variety of reasons electrical and electronic engineering, quite reluctant, to contribute their prime political science, and philosophy—were research output. Data showing that freely chosen with the expectation that they available articles in their discipline are would represent different points on the more likely to be cited is powerful evi- continuum of open-access adoption. They dence of the value of repositories as well also were selected as disciplines whose as other open-access channels. scholars have a tradition of active use of preprints. Ten leading journals in each The Research Question discipline, as defined by ISI’s Journal This study’s hypothesis is that scholarly Citation Reports (JCR) for 2002 were se- articles from disciplines with varying lected (except philosophy, where there is rates of open-access adoption have a no JCR).17 High-impact journals were se- greater research impact if the articles are lected as indicators of leading researcher freely available online than if they are behavior while making no assumptions not. To determine whether a difference about journal quality. Open-access articles in impact exists, the mean citation rates, published in lower-impact journals may, as recorded in the ISI Web of Science da- in fact, have a greater relative research tabase, of freely available articles (1) were impact because they are not so widely compared with those that are not (0) for available to authors through personal and a sample population of journal articles institutional subscriptions. in four disciplines. The null hypothesis ISI Web of Science citation data were is that there is no difference between the used as a measure of research impact. mean citation rates: H0: d1 = d0; H1: H0 is Although citations cannot in themselves false. be said to measure research impact, nev- These data