Surveys on sensitive topics

Andrew Sullivan (link) has a few questions about a new Pew survey focusing on the LGBT subpopulation. He wonders, for instance, about the high proportion of self-identified bisexuals in this poll.

What interests a statistician here is the fact that the poll deals with sensitive matters, which typically present a challenge in terms of survey response, and nonresponse bias. The main accommodation that the pollster (GfK) made here was to conduct an online survey because people apparently let their guards down in that medium.

Andrew also wondered about the fact that "only 28% of bisexuals have come out, compared to 77% of gay men, and 71% of lesbians," among the respondents. I find the concept that a closeted person would identify himself/herself to a pollster as LGBT to be inconsonant. But then, the pollster appeared to re-confirmed eligibility carefully. (After the recent revelation about online privacy, one thinks this might change.)

In any case, I am glad to see a very detailed description of the methedology. See here.