Lack of time, funds or other resources are the explanations that have been given by clinical researchers for failure to publish all the results of large randomised trials.1 It has been estimated that 40–62% of trials have introduced new variables into the study and/or omitted others.2 This insight has been gained by comparing trial protocols with publications. The International Clinical Trials Registry Platform was established in response to such observations. One goal was to prevent outcome reporting bias, that is, where only a selection of a trial's outcomes are reported, based on the result, leading to a biased view of an intervention's effect.3

Inspired by this, in 2007 the Cochrane Health Promotion and Public Health Field led the call for a register for public health interventions as well, adapted to the diversity of methods used to assess interventions in public health.4 The paper by Pearson and Peters in this …