ArticlePeerJ2018
The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles.
Article in PeerJ, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 206 papers, 5 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
206 citing papers in PubMed, 5 syntheses or guidelines pooled it.
- Advances in NLRP3 inflammasome research in viral infections: evolution, trends, and future directions.Frontiers in cellular and infection microbiology · 2026Pooled it
- Pooled it
- Pooled it
- Is the open access citation advantage real? A systematic review of the citation of open access and subscription-based articles.PloS one · 2021Pooled it
- The impact of institutional repositories: a systematic review.Journal of the Medical Library Association : JMLA · 2020Pooled it
- Finding Medical Photographs of Patients Online: Randomized, Cross-Sectional Study.Journal of medical Internet research · 2024Trial
- Trial
- Is it worth publishing Open Access? - the scientific impact of Open Access publications in the field of medical education.Medical education online · 2026Article
- Mapping the structure of an emerging field: A scientometric decoding of large language model applications in the dental field.The Japanese dental science review · 2026Article
- Validation design and experimental provenance shape apparent machine-learning transferability in legacy Mössbauer spectroscopy.RSC advances · 2026Article
- From Clinical Technique to Interprofessional Implementation and Intelligent Integration: A Bibliometric Analysis of the Interdisciplinary Expansion of Robot-Assisted Spine Surgery.The international journal of medical robotics + computer assisted surgery : MRCAS · 2026Article
- Reproducibility in biomedical research.Nature medicine · 2026Review
- Who Gets to Be Read? Factors Affecting Full-Text Access Rates in Periodontology and Implantology Research.International journal of dental hygiene · 2026Article
- Cleft Lip and Palate Publishing Trends From Authors in Low- and Middle-Income Countries in Cleft and Craniofacial Journals.The Cleft palate-craniofacial journal : official publication of the American Cleft Palate-Craniofacial Association · 2026Article
- Citation and policy influence of research using demographic and health survey data: a bibliometric analysis.Health research policy and systems · 2026Article
- Mapping the Landscape of Open Access Dashboards - A Dataset for Research and Infrastructure Development.Scientific data · 2026Article
- Review
- Promoting awareness of open access publishing in speech-language therapy and audiology: Lessons from multilingual language assessment research.The South African journal of communication disorders = Die Suid-Afrikaanse tydskrif vir Kommunikasieafwykings · 2026Article
- Review
- Authorship, titles and open access as drivers of citation performance in orthopaedics: a scientometric analysis.Journal of orthopaedics and traumatology : official journal of the Italian Society of Orthopaedics and Traumatology · 2026Article
146 more citing papers are in PubMed but not listed here.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
9 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
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.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.