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The Centers for Disease Control and Prevention is the latest group to attempt to estimate just how many people identify as a sexual orientation other than heterosexual. According to the CDC's National Health Interview Survey, the first broad government survey of sexual orientation, just under 3 percent of Americans identify as gay, lesbian and bisexual. Gays and lesbians make up 1.6 percent of the survey, bisexuals make up 0.7, and 96.6 percent of Americans identify as straight, based on a sample size of 33,557 adults between the ages of 18 and 64.

As The Washington Post wrote, from a health care point of view, identifying sexuality is an important step towards identifying the unique health needs of the LGBT community. But as far as quantifying how many Americans aren't heterosexual, the survey leaves something to be desired. It doesn't ask about respondent's gender identity and, as The Post noted, a small percentage of people needed more options: "an additional 1.1 percent declined to answer, responded 'I don’t know the answer' or said they were 'something else.'"

The survey comes up with a number that's lower than the 3.5 to 4 percent figure found in other surveys. And as we've seen from past surveys, what's asked matters. Specifically, the broadness of the answers available to respondents makes a difference.

In 2007, researchers at Cornell University interviewed 20,000 individuals in 80 communities. "Mostly heterosexual" was an option for respondents, and the results showed a higher percentage of nonheterosexuality, especially among women:

85.1% of the young women identified as heterosexual; 0.5% reported no sexual identity; and the remaining 14.4% were sexual but not strictly heterosexual, i.e. either lesbian or bisexual. Among young men, 94.0% identified themselves as heterosexual; 0.4% of the men reported no sexual identity; and the remaining 5.6% identified as gay or bisexual. 

In 2012, Gallup asked 121,290 individuals "Do you, personally, identify as lesbian, gay, bisexual, or transgender?" and found that 3.4 percent identify as LGBT. Gallup explained the difficulty in getting a complete number with this:

Measuring sexual orientation and gender identity can be challenging since these concepts involve complex social and cultural patterns. As a group still subject to social stigma, many of those who identify as lesbian, gay, bisexual, or transgender may not be forthcoming about this identity when asked about it in a survey. Therefore, it's likely that some Americans in what is commonly referred to as "the closet" would not be included in the estimates derived from the Gallup interviews. 

What we do know for sure is that, based on the data available, people tend to overestimate the number of LGBT Americans. According to a 2011 Gallup poll, only 4 percent of Americans guessed that less than 5 percent of the population is gay or lesbian (again, that doesn't account for bisexual, "I don't know the answer" or "something else").

And that, too, has policy implications. As The Atlantic noted, "people who overestimate the percent of gay Americans by a factor of 12 seem likely to also wildly overestimate the cultural impact of same-sex marriage." At the same time, this "may reflect a triumph of the gay and lesbian movement's decades-long fight against invisibility and the closet." Despite its limitations, the CDC survey represents a small victory in the fight against the invisibility of the way sexual orientation and health interact. 

This article is from the archive of our partner The Wire.