The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles.
The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles.
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作者：
Piwowar H;Priem J;Larivière V;Alperin JP;Matthias L;Norlander B;Farley A;West J;Haustein S
尽管对学术文献的开放访问（OA）越来越兴趣，但对评估OA的患病率和特征的大规模，最新和可重现的研究的需求尚未满足。我们使用Oadoi（一项开放的在线服务，确定了6700万篇文章的OA状态）来满足这种需求。我们使用三个样本，每本100,000篇文章，调查三个人群的OA：（1）所有期刊文章分配了Crossref doi，（2）最近在Web of Science中索引的期刊文章，以及（3）UnpayWall的用户查看的文章，一种开源浏览器扩展程序，可让用户使用OADOI查找OA文章。我们估计，至少有28％的学术文献是OA（总计19m），并且这一比例正在增长，特别是由于黄金和杂种的增长而驱动。最近分析（2015年）的OA百分比最高（45％）。由于这种增长，以及读者不成比例地访问新文章的事实，我们发现Untaywall用户经常遇到OA：他们认为的文章中有47％是OA。值得注意的是，OA最常见的机制不是黄金，绿色或混合动力OA，而是我们配音青铜的类别不足的类别：无明确的开放许可证在出版商网站上免费阅读的文章。我们还研究了OA文章的引文影响，证实了所谓的开放式引文优势：对年龄和纪律的核算，OA文章的引用比平均水平高出18％，这是主要由绿色和杂种OA驱动的效果。我们鼓励使用免费的Oadoi服务进行进一步的研究，以告知OA政策和实践。
Despite growing interest in Open Access (OA) to scholarly literature, there is an unmet need for large-scale, up-to-date, and reproducible studies assessing the prevalence and characteristics of OA. We address this need using oaDOI, an open online service that determines OA status for 67 million articles. We use three samples, each of 100,000 articles, to investigate OA in three populations: (1) all journal articles assigned a Crossref DOI, (2) recent journal articles indexed in Web of Science, and (3) articles viewed by users of Unpaywall, an open-source browser extension that lets users find OA articles using oaDOI. We estimate that at least 28% of the scholarly literature is OA (19M in total) and that this proportion is growing, driven particularly by growth in Gold and Hybrid. The most recent year analyzed (2015) also has the highest percentage of OA (45%). Because of this growth, and the fact that readers disproportionately access newer articles, we find that Unpaywall users encounter OA quite frequently: 47% of articles they view are OA. Notably, the most common mechanism for OA is not Gold, Green, or Hybrid OA, but rather an under-discussed category we dub Bronze: articles made free-to-read on the publisher website, without an explicit Open license. We also examine the citation impact of OA articles, corroborating the so-called open-access citation advantage: accounting for age and discipline, OA articles receive 18% more citations than average, an effect driven primarily by Green and Hybrid OA. We encourage further research using the free oaDOI service, as a way to inform OA policy and practice.