Data sharing after publication

A paper published in PLoS ONE (Empirical Study of Data Sharing by Authors Publishing in PLoS Journals) last week highlighted the very important issue of data sharing by authors after publication. The small study, of 10 papers published in PLoS Medicine and PLoS Clinical Trials, found that of  ten requests for raw data, “three investigators did not respond, four authors responded and refused to share their data, two email addresses were no longer valid, and one author requested further details. A reminder of PLoS’s explicit requirement that authors share data did not change the reply from the four authors who initially refused. Only one author sent an original data set.”

Although the study is very small, and the lack of response was due to a number of differing issues including incorrect email addresses for two authors, nevertheless, the study raises important questions about whether authors really understand what journals’ policies on requiring data sharing means, whether they are willing to abide by such policies, and what journals can do to enforce such policies.

Our policies state

“Data Availability

Open access applies to both the scientific literature and the data used to establish that literature. Publication is contingent on making data integral to a manuscript freely available without restriction, provided that appropriate attribution is given and that suitable mechanisms exist for sharing the data used in a manuscript and that in the case of clinical information patient confidentiality is not compromised.

1. Data for which public repositories have been established that are in general use should be deposited before publication, and the appropriate accession numbers or digital object identifiers published with the paper.
2. If an appropriate repository does not exist, data should be provided as supporting information with the published paper. If this is not practical, data should be made freely available upon reasonable request.
3. The conclusions of a study must not be dependent solely on the analysis of proprietary data. If proprietary data were used to reach a conclusion, and the authors are unwilling or unable to make these data public, then the paper must include an analysis of public data that validates the conclusions so that others can reproduce the analysis and build on the findings.

Note that any restrictions on the availability or on the use of datasets might be judged to diminish the significance of a paper and will therefore influence the decision about whether a paper should be published. These policies have been developed in accordance with the principles established in Sharing Publication-Related Data and Materials (National Academies Press, 2003).”

We do not know who the authors contacted by Vickers and Savage were. During the review process of the Vickers paper at PLoS we offered to ourselves contact these authors, but the investigators declined. It is possible (though not an excuse) that the authors contacted by Vickers and Savage did not take the request as seriously as they should—indeed, as the investigators noted in the PLoS ONE paper “Our method of requesting data sets was intentionally left vague as we were interested as much in the investigators responses as acquiring the actual data set; perhaps a more detailed request would have garnered more positive responses.”

We would hope that the investigators’ conclusion that “our findings suggest that explicit journal policies requiring data sharing do not lead to authors making their data sets available to independent investigators” would not prove to be generally true.  However, even if these authors are not representative more generally of PLoS authors, the findings remain troubling. We take the issue of data sharing very seriously—if we are made aware of failure to comply with our policy of data sharing will gladly contact authors ourselves. On occasion, as in one recent case, a reason for non-compliance may become apparent, i.e., that supplying data would have compromised patient confidentiality. In other cases where we have contacted authors, they have quickly complied.

We will be looking at the language on our instructions and ensuing authors are aware of it at submission. The scientific world expects authors to be able to stand by their results; a critical part of this is making the data available if others need it. Non compliance for trivial reasons is not acceptable. At PLoS Medicine should an author fail to comply we would consider it appropriate to post a note on the online paper to that effect. In disagreements involving requests for data, we may also refer the requestor to officials at the author’s institution, or vice versa.