Several common sense strategies are effective

Papers p 1183

Most readers of the BMJ probably receive postal questionnaires from time to time. Whether such questionnaires are dutifully completed and returned, left to gather dust, or rapidly thrown away may seem like a random process of little importance. However, while response may be of little consequence at the individual level, for many research studies a high response rate to a postal questionnaire is critical. No matter how expensive, well designed, or important a study, a poor response rate can introduce such uncertainty—and worse still, bias—in the results as to make the study of little scientific value. However, postal questionnaires are attractive to researchers because they are likely to be substantially cheaper than data collection based on interviews. Postal questionnaires are increasingly used in other areas of health care, for example in screening programmes, to assess patient satisfaction, or to assess outcomes after treatments such as surgery. Methods to maximise response rates from postal questionnaires therefore have considerable relevance for medical researchers, practitioners, and policy makers alike.

In this issue Edwards and …