• How many LGBT people are there?

    Knowing how many lesbian, gay, bisexual, or transgender (LGBT) people there are matters for health policy. Gay men have an elevated HIV risk. LGBT kids have a higher risk of suicide. But no one knows this number. Recent surveys estimates range from 2% to 6% of the population.

    However, there are compelling new data suggesting that whatever the number is, current survey methods underestimate it. Because there is still stigma associated with same sex desire and behaviour, some people are reluctant to answer survey questions truthfully. Similarly, there are many other health behaviours whose prevalence is difficult to estimate including smoking, alcohol consumption, illicit drug use. So it’s possible that even on anonymous surveys, people under-report sensitive behaviors.

    But if people under-report even when they are promised anonymity, how can we  estimate the true prevalence of LGBT orientation? Katherine Coffman, Lucas Coffman, and Keith Ericson have a clever way at getting at this question:

    a randomly chosen control group of participants is asked to report how many of N items are true for themselves, where the items are neutral and non-sensitive in nature. The rest of the respondents report how many of N+1 items are true, with N items being identical to the control group’s items, and the N+1st item being a sensitive item, e.g. “I am not heterosexual”. With a large enough sample, the researcher can estimate the population mean for the N+1st item, the sensitive item, by differencing out the mean of the sum of the N other items as estimated from the control group.

    The Coffmans estimated how badly current survey methods underestimate LGBT orientation by comparing two ways of asking sensitive questions. The first way was the standard survey method, that is, directly asking anonymous respondents about their sexual orientation. The second way was the “veiled” method described above:

    The veiled method increased self-reports of non-heterosexual identity by 65% (p<0.05) and same-sex sexual experiences by 59% (p<0.01).

    The Coffmans also used the same design to find out whether survey respondents accurately report whether they hold socially undesirable attitudes like prejudice against gays or lesbians:

    The veiled method also increased the rates of anti-gay sentiment. Respondents were 67% more likely to express disapproval of an openly gay manager at work (p<0.01) and 71% more likely to say it is okay to discriminate against lesbian, gay, or bisexual individuals (p<0.01).

    Overall:

    The results show non-heterosexuality and anti-gay sentiment are substantially underestimated in existing surveys, and the privacy afforded by current best practices is not always sufficient to eliminate bias.

    So there may be quite a few more LGBT people than we thought there were. Should that change anyone’s beliefs about whether same sex desire and behaviour are licit? In my view, there is no ‘moral question’ about the legitimacy of same sex desire or behaviour, just as there is no moral question about eating hot sauce on scrambled eggs. But suppose that there was a question about this. It is unclear how that question would depend on the prevalence of same sex desire or behaviour.

    Bill_Gardner

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