A statistician friend of mine told me of an interesting technique used to obtain honest responses on surveys that dealt with sensitive issues. I recall the general gist of the method, but am wondering if anyone knows the details and if it is referenced anywhere.
The story was that the Florida AMA wanted to assess drug use among physicians. They sent out a questionnaire with one die. IIRC, the instructions were something along the lines of "roll the die. If you have ever taken drugs or get a 6, write down six; otherwise write down whatever number comes up". The idea being that if someone pulled the doctor's questionnaire and saw a six, he could say he didn't take drugs, he just happened to roll a six.