ABSTRACT
Two groups were mailed questionnaires. The first group consisted of the Society for Psychophysiological Research (SPR). "The SPR survey was mailed ... along with a stamped return envelope and reply card [that identified them] that respondents were asked to mail under separate cover after they had mailed their survey. In this way, anonymity was assured while making it possible to track respondents. Within about 2 weeks of this mailing, a postcard was sent to prompt responding. About 3 weeks after the initial mailing, nonresponders were sent a second survey with return envelopes and postcards. Approximately 7 weeks after the initial mailing, this process was repeated, with nonresponders receiving a personalized note exhorting them to complete the survey."
