For some time the BMJ has been watching other journals’ efforts to encourage authors to make raw research data available. Now we are taking part too, by asking authors to include a data sharing statement at the end of each original research article. The statement will explain which additional data—if any—are available, to whom, and how. Those data could range from additional explanatory material to the complete dataset. People allowed access to the data might range from fellow researchers to everyone. And data might be available only on request, accessible online with a password, or openly accessible to all on the web with a link on bmj.com.

We understand that many authors wish to guard data until they have published all their own papers, and we know that data sharing is hard to do. But we hope that authors will, increasingly, set the data free, perhaps after a set period of personal use.

Data sharing means more than the open access publication of articles and the posting in online registries of study protocols and main results. Sharing allows other researchers—and perhaps scientists, clinicians, and patients—access to raw numbers, analyses, facts, ideas, and images that do not make it into published articles and registries. At its fullest extent, data sharing means free access …