Increasing response rates in physicians' mail surveys: an experimental study.

It is becoming increasingly difficult to obtain high response rates in physicians' mail surveys. In 1983-84, we tested the effectiveness of two techniques among 604 Quebec physicians who had not responded to an initial letter. A handwritten thank you note at the bottom of the letter accompanying the questionnaire and a more personalized mailout package increased response rates by 40.7 per cent and 53.1 per cent, respectively, compared to control groups.