This week the BMJ publishes a paper (doi: 10.1136/bmj.a568) that has nothing directly to do with medicine or health care.1 It does, however, have everything to do with access to research results, a topic that should interest authors and readers in any field. The paper asks whether open access (free full text online publication) increases the chances of an article being read and cited compared with subscription access publication (where articles are accessible only to individuals or institutions who pay to subscribe).

It is a question that many have asked and tried to answer since academics first challenged the subscription based publishing model over 10 years ago. Open access offered an end to what they saw as profiteering by publishers at the expense of the academic community. It restored a public good. If it could also offer higher usage and citation rates, this was icing on the cake. Authors who submitted their work to open access journals might be rewarded with greater visibility, and publishers who launched open access titles or converted existing ones to open access might see their usage figures and impact factors rise.

Studies in various disciplines have explored this possibility.2 Most have found a correlation between usage and citation rates, as well as a citation advantage from open access. However, all of these have been retrospective observational studies. In what is, to the best of our knowledge, the first randomised trial of open access, Davis and colleagues sampled papers due …