Anomalies in Open-Access & Traditional Biomedical Literature: A Comparative Analysis Abstract This research compares rates of anomaly and post-publication modification of open access and traditionally published journal articles in the biomedical sciences. Preliminary results indicate that open access journals do not show a higher incidence of post-publication modification than traditionally published journals. Abstract This research compares rates of anomaly and post-publication modification of open access and traditionally published journal articles in the biomedical sciences. Preliminary results indicate that open access journals do not show a higher incidence of post-publication modification than traditionally published journals. Open Access Biomedical Literature Open access journals are characterized by: “free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited." [2] Open access publishing is growing in the biomedical sciences. In 2004 WoS included 239 Open Access biomedical journals. At least 280 journals found in the Directory of Open Access Journals ( are currently indexed for Medlinewww.doaj.org 20% of journals indexed in Medline offer free, full-text access via PubMed Central (1080/5487) Open Access Biomedical Literature Open access journals are characterized by: “free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited." [2] Open access publishing is growing in the biomedical sciences. In 2004 WoS included 239 Open Access biomedical journals. At least 280 journals found in the Directory of Open Access Journals ( are currently indexed for Medlinewww.doaj.org 20% of journals indexed in Medline offer free, full-text access via PubMed Central (1080/5487) Research design The sample was generated by identifying 12 open access medical and life science journals with particularly high impact factors. [1] Using data from Journal Citation Reports 2009, these journals were then paired with fee-based access journals with comparable subjects and impact factors. An advanced search of PubMed for these journal pairs and document types "Publication of Retraction", "Correction & Republication" and "Publication of Errata" from the last 10 years yielded 27 anomalous articles from a pool of approximately 76,000 articles. Subsequently, all anomalous articles from July were retrieved, yielding 1681 articles. Of these, full-text access is available for 353 on PubMed Central, 73 from DOAJ.org, and 47 are available from Web of Science. Research design The sample was generated by identifying 12 open access medical and life science journals with particularly high impact factors. [1] Using data from Journal Citation Reports 2009, these journals were then paired with fee-based access journals with comparable subjects and impact factors. An advanced search of PubMed for these journal pairs and document types "Publication of Retraction", "Correction & Republication" and "Publication of Errata" from the last 10 years yielded 27 anomalous articles from a pool of approximately 76,000 articles. Subsequently, all anomalous articles from July were retrieved, yielding 1681 articles. Of these, full-text access is available for 353 on PubMed Central, 73 from DOAJ.org, and 47 are available from Web of Science. Introduction Open access publishing is gaining increasing prominence in the biomedical literature; of the 20 most highly ranked medical and life science journals, (as sorted by impact factor by Journal Citation Reports), 7 provide free public access to content. This study compares open access and traditional, subscription-based biomedical literature for differences in the incidence of retraction, correction & republication or publication of errata. If there is no difference between the groups, or open access publications have fewer anomalies, the data suggest that open access publications are not more likely to publish flawed literature, despite differences in editorial and publishing practices. Introduction Open access publishing is gaining increasing prominence in the biomedical literature; of the 20 most highly ranked medical and life science journals, (as sorted by impact factor by Journal Citation Reports), 7 provide free public access to content. This study compares open access and traditional, subscription-based biomedical literature for differences in the incidence of retraction, correction & republication or publication of errata. If there is no difference between the groups, or open access publications have fewer anomalies, the data suggest that open access publications are not more likely to publish flawed literature, despite differences in editorial and publishing practices. Address for correspondence: Gabriel M. Peterson North Carolina Central University School of Library and Information Sciences 321 Shepard Library, Durham, NC 27707, USA Address for correspondence: Gabriel M. Peterson North Carolina Central University School of Library and Information Sciences 321 Shepard Library, Durham, NC 27707, USA Gabriel M. Peterson, PhD School of Library and Information Sciences – North Carolina Central University References [1] McVeigh ME (2004) Open access journals in the ISI citation databases: Analysis of impact factors and citation patterns. Available: ​ 4. Accessed http:// ​ 4 [2] Anonymous (2002 February) Budapest Open Access Initiative. Available: Accessed http:// [3] Eysenbach G, 2006 Citation Advantage of Open Access Articles. PLoS Biol 4(5): e157. doi: /journal.pbio Accessed References [1] McVeigh ME (2004) Open access journals in the ISI citation databases: Analysis of impact factors and citation patterns. Available: ​ 4. Accessed http:// ​ 4 [2] Anonymous (2002 February) Budapest Open Access Initiative. Available: Accessed http:// [3] Eysenbach G, 2006 Citation Advantage of Open Access Articles. PLoS Biol 4(5): e157. doi: /journal.pbio Accessed Poster presented at the 2010 Annual Meeting of the. American Society of Information Science & Technology,, , Pittsburgh, PA Incidence of post-publication modification of Open Access and Traditional biomedical literature, Implications for researchers The open-access biomedical literature does not contain more anomalies than traditionally available, fee-for-access literature, though approximately 13,500 more articles were published in open-access journals than traditional ones in this time. Open access literature has higher rates of citation than other literature, yet increased scrutiny has not resulted in higher levels of post-publication modification. Research published using the open access model appears to be as reliable as traditionally available scholarly literature. Implications for researchers The open-access biomedical literature does not contain more anomalies than traditionally available, fee-for-access literature, though approximately 13,500 more articles were published in open-access journals than traditional ones in this time. Open access literature has higher rates of citation than other literature, yet increased scrutiny has not resulted in higher levels of post-publication modification. Research published using the open access model appears to be as reliable as traditionally available scholarly literature. t-score of yields a p-value of (8 df) The hypothesis that there is a statistically significant difference in the incidence of post-publication modification of open access and traditionally published biomedical literature is rejected. OAJ NameTotal PPMImpact factorTJ NameTotal PPM2Impact factor3 British Medical Journal ANNALS OF INTERNAL MEDICINE Journal of Clinical Investigation JOURNAL OF EXPERIMENTAL MEDICINE Emerging Infectious Diseases ARCHIVES OF INTERNAL MEDICINE Molecular Vision EXPERIMENTAL EYE RESEARCH International Journal of Molecular Medicine Statistics in medicine t-score of yields a p-value of (8 df) Reject the hypothesis that there is a statistically significant difference in incidence of post-publication modification of biomedical literature between open access and traditional publishing models. Percentage of anomalous literature in PMC journals: 21% (353/1681) Percentage of PMC journals to total indexed in Medline: 20% (1080/5487) Incidence of anomaly in highly cited biomedical articles, : Open Access: 11 Fee-for-Access: 16