“Open access – free access to scholarly publications – offers many advantages. As surveys show, however, some researchers still have reservations. In the past decade, numerous empirical studies have been published providing substantiated results on the hopes and concerns regarding open access….

To conduct this review, TIB identified a total of 318 scientific studies that empirically examine various effects of open access. From this corpus, the authors selected 61 particularly relevant studies for a systematic comparison; these were then analysed thoroughly and the various results were compared in detail.

The effects studied relate to seven major aspects of open access:

Attention in the scientific community
Quality of scientific publications
Knowledge transfer
Productivity of the publishing system
Use of publications
Inequality in the science system
Economic impact on the publishing system…

Dr. David Hopf, lead author of the study, reported the key findings: “The literature reviewed confirms several advantages of open access: open access leads to increased usage and to a professionally and geographically more diverse readership. At the same time, open access publications make a greater contribution to knowledge transfer than traditionally published research results, and the publishing process – the time between the submission and acceptance or publication of articles – is shorter. What is more, a number of negative concerns assumed in relation to the effects of open access – for example, that open access publications are of an inferior quality and lead to disadvantages in print edition sales – have been dispelled.”

However, one partial result came as a surprise: the fact that open access publications are cited more frequently than publications that are not freely available is often mentioned as an advantage of open access – and is also confirmed by most empirical studies. However, a substantial proportion of the empirical literature deviates from this result, which means that an OA citation advantage cannot be conclusively confirmed empirically. In light of a high level of plausibility and methodological difficulties in this area, however, it can still be assumed that such an advantage exists.

Just one finding indicates a negative effect of open access: where so-called article processing charges (APCs) – publication costs incurred by many open access publications – exist, authors with fewer resources may be discouraged from publishing open access, e.g. due to low income levels in some regions of the world or a lack of institutional funding. However, this is not an effect of open access per se, but rather an effect of a particular business model for financing open access publications….”