Humphreys revealed his role to some of those he observed, but he noted that those who tended to talk with him openly were better educated; as he continued his research, he decided to conceal his identity in order to avoid response bias. Humphreys' rationale was that because of public stigma associated with the homosexual activities in question, and his subjects' desires to keep their activities secret, many were unlikely to allow him an opportunity for observation and follow-up interview were he to reveal himself as a researcher.