Le rapport donne un aperçu de l'état de la recherche - basé sur l'analyse de plusieurs dizaines d'études menées entre 2010 et 2021 - sur les différents effets du libre accès. Il  identifie également les aspects de l'impact du libre accès qui sont potentiellement très pertinents mais qui n'ont pas encore été suffisamment étudiés.

Effects of Open Access. Literature study on empirical research 2010–2021

David Hopf (Leibniz-Universität Hannover Philosophische Fakultät Hanovre)
Sarah Dellmann (Technische Informationsbibliothek (TIB) Hanovre)
Christian Hauschke (Technische Informationsbibliothek (TIB) Hanovre)
Marco Tullney (Technische Informationsbibliothek (TIB) Hanovre)

Mai 2024

Executive Summary

Open access—the free availability of scholarly publications—intuitively offers many benefits. At the same time, some academics, university administrators, publishers, and political decision-makers express reservations. Many empirical studies on the effects of open access have been published in the last decade. This report provides an overview of the state of research from 2010 to 2021. The empirical results on the effects of open access help to determine the advantages and disadvantages of open access and serve as a knowledge base for academics, publishers, research funding and research performing institutions, and policy makers. This overview of current findings can inform decisions about open access and publishing strategies. In addition, this report identifies aspects of the impact of open access that are potentially highly relevant but have not yet been sufficiently studied.

What has been researched?

In a comprehensive literature search, we identified 318 academic studies that empirically analyse various effects of open access. From this corpus, 61 particularly relevant studies were selected for a systematic comparison and were then analysed in detail. The main topics of the studies were categorised into seven impact areas.

What is the state of research on the effects of open access?

In the following section, we present the results of our analysis of the empirical literature on the effects of open access in the seven impact areas. It should be noted that the 2 potential for generalizing statements on some of the effects is limited by the fact that the international publishing system may be influenced by a variety of conditions. In addition, randomised studies, which could systematically control possible confounding factors, are not only rare in this area of investigation, but also very difficult to conduct.

1. Attention from the academic world: The majority of studies confirm a citation advantage for open access publications. However, there is also a non-negligible number of studies that report no citation advantage. The generalisability of the statements in this impact area is therefore limited: The existence of an open access citation advantage cannot be regarded as completely empirically confirmed. However, this does not mean that the open access citation advantage has been proven to be non-existent; a citation advantage for open access publications can still be reasonably assumed.

2. Quality of scholarly publications: In the studies analysed, no differences in quality between open access publications and closed access publications were found.

3. Knowledge transfer: The studies analysed show a significantly higher number of references from the non-academic sector (patents, news, court documents) to open access publications. This means that open access improves the knowledge transfer to society.

4. Productivity of the publication system: The analysed studies come to different conclusions. Neither an increase nor a decrease in the volume of publications due to open access can be universally claimed. Studies on the duration of the publishing process show that open access shortens the time between submission and acceptance or publication of articles.

5. Use of publications: The analysed studies report significantly higher download numbers and page views for open access publications. This implies that open access publications are used more often than nonopen access works.

6. Inequality in the science system: Several studies report that open access business models with Article Processing Charges (APCs) lead to lower participation of certain groups of authors: authors at financially disadvantaged institutions, authors in the Global South, and authors outside of the higher education sector are particularly disadvantaged. At the same time, other studies show that open access publications are used by a more diverse audience than closed access publications. The diversity of both authors and users is considered as an indicator of the representation of different groups of people and therefore as an indicator of inequality in the science system.

7. Economic impact on the publishing system: A number of studies containmodel-based results on the costs of various open access scenarios. However, the potential for generalisation of these results is low, as the studies analysed here are highly context-dependent. Other studies show that there is no 3 correlation between the (parallel) publication of books in open access and the sales figures of a print edition.

Which questions have not yet been researched?

Surveys show that the effects of open access on academic careers are considered important. However, there are no studies that provide sufficient empirical confirmation for this connection. The impact of open access on specific groups of participants (e.g. researchers outside well-funded academic institutions or people of different genders) is also under-researched. Finally, correlations between the individual effects of open access have not yet been sufficiently analysed empirically.


Based on these results, it is recommended:

R1 to further expand open access activities,

R2 to close the research gaps mentioned (effects not yet investigated),

R3 to carry out additional studies that provide further evidence concerning certain effects

R4 to take action to counter the negative, inequality-increasing effects of APCs.

Overall conclusion

Overall, various advantages of open access can be considered as empirically confirmed by the current state of research. These advantages include improved knowledge transfer, increased speed in the publishing process and increased use by a professionally and geographically diverse readership. At the same time, some presumed negative effects of open access—such as lower quality of publications and disadvantages in the sale of print editions—can be regarded as empirically refuted. The empirical results on the effects of open access therefore support the aim of a far-reaching transition to open access, to which German academic organisations, among others, have committed themselves.



1 Executive Summary 2 Introduction 3 Method 4 Results & Discussion of the impact areas

4.1 Attention from the academic world

4.2 Quality of scholarly publications

4.3 Knowledge transfer

4.4 Productivity of the publishing system

4.5 Use of publications

4.6 Inequality in the science system

4.7 Economic impact on the publishing system

4.8 Summary of the Results

5 Research Gaps 6 Conclusion

6.1 Connections between impact areas

6.2 Recommendations

6.3 Limitations

6.4 Concluding remarks


A Details on the literature research