Effects of disseminating research findings on response rates in a community survey: a randomised controlled trial.

Response rates to postal questionnaire surveys are declining, particularly in areas of deprivation. These may limit the external and internal validity of the findings of such studies. A recent systematic review identified interventions that may be effective in improving response rates although no trial was identified that evaluated the effectiveness of feeding back research findings to respondents. As part of an evaluation of the health impacts of building a traffic calming scheme, we surveyed local residents six months before (first survey) and six months after (second survey) the scheme was built. We carried out a randomised controlled trial to evaluate the effects of a study feedback information leaflet on response rates to the second postal questionnaire survey.