Global scale across multiple dimensions
The analysis covers 19 million outputs and 420 million citation links, measuring diversity by institutions, countries, subregions, regions, and fields of research.
↳ Contribution and Method, pp. 827–833
Abstract
Abstract The goal of open access is to allow more people to read and use research outputs. An observed association between highly cited research outputs and open access has been claimed as evidence of increased usage of the research, but this remains controversial. A higher citation count also does not necessarily imply wider usage such as citations by authors from more places. A knowledge gap exists in our understanding of who gets to use open access research outputs and where users are located. Here we address this gap by examining the association between an output’s open access status and the diversity of research outputs that cite it. By analysing large-scale bibliographic data from 2010 to 2019, we found a robust association between open access and increased diversity of citation sources by institutions, countries, subregions, regions, and fields of research, across outputs with both high and medium–low citation counts. Open access through disciplinary or institutional repositories showed a stronger effect than open access via publisher platforms. This study adds a new perspective to our understanding of how citations can be used to explore the effects of open access. It also provides new evidence at global scale of the benefits of open access as a mechanism for widening the use of research and increasing the diversity of the communities that benefit from it.
Key Claims
Primary findingSupported
we found a robust association between open access and increased diversity of citation sources by institutions, countries, subregions, regions, and fields of research, across outputs with both high and medium–low citation counts
Possible — the claim's weakest requirement is that the effect exists at all. Based on how the study was designed and conducted, not on statistics extracted from the paper. Experimental. Every point below is traceable to a quoted passage, but this forecast has not yet been validated against known replication outcomes.
large observational corpus and extensive robustness checks support direction, but residual selection and coverage limitations remain
Abstract; Results
SecondarySupported
Open access through disciplinary or institutional repositories showed a stronger effect than open access via publisher platforms.
GREEN generally exceeds GOLD across reported comparisons, though overlapping categories and residual selection limit interpretation
Abstract; Results, Comparing OA categories
SecondaryTentative
It also provides new evidence at global scale of the benefits of open access as a mechanism for widening the use of research and increasing the diversity of the communities that benefit from it.
observational citation diversity cannot identify OA-caused wider use or the full communities benefiting
Abstract; Conclusion
SecondarySupported
the citation diversity advantage also accrues preferentially to traditionally prestigious centres of research.
regional citation-flow patterns support the direction, with incomplete bibliographic coverage limiting geographic inference
Results, Comparing geographies; Discussion
Derived from the full evaluation — not a separate score.
Strengths · Limitations
Strengths
Extensive internal robustness analyses
The reported pattern is checked across publication years, two diversity indices, OA categories, equal-sized samples, fields, and 14 citation-count bins.
↳ Robustness of results, pp. 837–840; Supplementary Figures A–N
Substantive engagement with competing explanations
The paper discusses randomized null results, author self-selection, prestige, discipline, and resource access, then explicitly limits its conclusion to an observational association.
↳ Introduction, p. 826; Results, p. 836; Discussion, pp. 840–841
Limitations
Residual OA selection remains unresolved
Citation-count stratification reduces one source of confounding but does not independently adjust for discipline, institutional prestige, author characteristics, or research-resource context.
↳ Method, p. 827; Results, pp. 834–836; Discussion, pp. 840–841
Coverage bias is not quantified
Crossref-only DOI coverage, MAG inclusion, and the exclusion of outputs with fewer than two citations constrain regional and disciplinary generalization without quantitative bias bounds.
↳ Input data, pp. 832–833; Data limitations, pp. 841–842
Benefit language exceeds the design
The Abstract describes OA as a mechanism widening use, and the Conclusion treats diverse citing outputs as wider use, although the study identifies an observational association in a narrow proxy.
↳ Abstract, final sentence; Conclusion, pp. 842–843
Nabu Commentary
The study’s contribution rests on combining global scale with a citation-diversity framing that extends beyond conventional citation counts. The methodology gains credibility from repeated analyses across time, measures, OA categories, fields, samples, and citation-count bins, but those checks do not fully adjust for selection into OA or quantify bibliographic coverage bias. The paper’s literature positioning and limitations discussion are substantive, including explicit treatment of randomized null evidence and regional data gaps. Scores are moderated chiefly because some Abstract and Conclusion wording turns an observational citation association into stronger claims about OA-driven benefits and wider use.
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Author Note / Field Feedback
Nabu’s assessment, alongside the field’s view.
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Dimension breakdown
Study Quality
Sound3.6
Confidence mediumContribution
3.9
The study extends citation-diversity analysis from narrow prior samples to 19 million outputs and five institutional, geographic, and disciplinary groupings. The advance is meaningful but uses standard diversity indices in an observational extension rather than introducing causal identification or a new analytic method.
Contribution, pp. 827–828; Relevant research, pp. 826–827
“making it the largest study of this type to date”
Methodological Rigour
3.3
The workflow defines the corpus, two diversity indices, and extensive checks across years, measures, citation bins, samples, fields, and OA categories. Crossref/MAG selection and classification errors are not quantitatively bounded, and citation-count stratification does not resolve all residual OA-selection confounding.
Method, pp. 827–834; Robustness of results, pp. 837–840; Data limitations, pp. 841–842
“our analysis is not able to confirm the exact causal links”
Reporting
3.6
The article has a coherent progression from motivation and methods through results, robustness, limitations, and conclusion. Reporting is reduced when the Abstract and Conclusion describe causal benefits and wider use more strongly than the observational citation proxy establishes.
Abstract, final sentence; Results, p. 836; Conclusion, pp. 842–843
“benefits of open access as a mechanism for widening the use of research”
Positioning
3.9
The paper engages randomized null evidence, self-selection, prestige, disciplinary confounding, and the two closest diversity studies. Its limitations discussion connects coverage problems to regional findings, although the magnitude of those effects on the headline association is not quantitatively bounded.
Introduction, p. 826; Relevant research, pp. 826–827; Discussion and Data limitations, pp. 840–842
“there may be limitations in our coverage of certain areas of Asia, Sub-Saharan Africa and other regions”
Reliability
Caveats4 of 4 checks
Internal CoherenceNoted
The reported corpus, methods, and descriptive findings are internally consistent, and the paper explicitly disclaims causal identification. Some Abstract, Results, and Conclusion wording nevertheless shifts from association in citation-based proxies toward causal benefits and wider use.
Research ConductNoted
Funding and competing interests are disclosed, the study uses bibliographic metadata rather than human-subject data, and processed data and analysis code are claimed available through Zenodo and GitHub. One or more identifiers named in the paper's availability or registration statements did not resolve when checked on 2026-09-28T16:08:08.243051+00:00: https://github.com/Curtin-Open-Knowledge-Initiative/citation-diversity. Recorded as a discrepancy between the paper's claims and the cited sources; not an assessment of the underlying research.
Flags: 3 declared / 5 total
Reference IntegrityClean
21 of 21 checkable references verified
25 references in manuscript 4 are books, websites or datasets — counted, but not index-checkable
Post-Publication RecordClean
No retraction notice found in Retraction Watch.
Last checked: 28 Sep 2026
Sources: Retraction Watch ✓
Readiness
Where this paper’s evidence sits on the path from initial observation to real-world use.
Demonstrated
The measures are demonstrated on real bibliographic data, but the paper offers indicators and policy insights rather than an operational decision tool. Causal uncertainty and the lack of implementation guidance leave additional work before practitioners could act directly.
Results, p. 836; Conclusion, pp. 842–843
“a guide to improving our policy implementation of OA”
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