In 2001, Kerith Conron was working on LGBT issues in Boston’s health department. She discovered that homeless transgender people were sleeping on benches because the shelters, which were segregated by gender, didn’t know what to do with them. As a result, transgender people weren’t included in the city’s assessment of who needed shelter.

Conron, now a research scientist at the Fenway Institute, a research center specializing in LGBT health, says going uncounted means being overlooked, “and if you’re overlooked, you’re at greater risk of being underserved.” But how we count matters, too. She believes that quantifying a community at the city or even the state level isn’t enough — national statistics are necessary to truly understand the number of transgender Americans and their needs.

There are signs that American society is increasingly willing to acknowledge the transgender community. In February, no less a cultural force than Facebook added more than 50 custom gender options — from gender nonconforming to pangender — for its users.

But counting the transgender population nationally remains a steep challenge. The U.S. Census Bureau doesn’t ask who is transgender, nor do the Centers for Disease Control and Prevention. But even if they did, the responses might not be reliable because some people are afraid to answer, while others disagree on what “transgender” even means. If you see someone cite a statistic about transgender people in the United States, you’re seeing a rough estimate at best.

Gary Gates is an LGBT demographer at the University of California Los Angeles School of Law’s Williams Institute, which studies sexual orientation and gender identity law and public policy. He is responsible for one of the most frequently cited estimates of the transgender population — 700,000, about 0.3 percent of U.S. adults. That figure is based on data from two surveys. One, conducted in Massachusetts in 2007 and 2009, found that 0.5 percent of respondents ages 18 to 64 identified as transgender. The other, done in California in 2003 to look at trends in LGBT tobacco use, found that 0.1 percent of adults in California identified as transgender. Using the surveys to get to the 0.3 percent estimate “takes a lot of statistical gymnastics,” Gates said.

He acknowledged his estimate has “substantial limitations,” adding that the only way to do better is to use nationwide surveys.

Gates has spent most of his career trying to convince survey writers to better include LGBT Americans in their research. Major breakthroughs have been made. In 2013, after years of consultation, the CDC’s National Health Interview Survey included a section on sexual orientation. As a result, nationally representative data is available for the first time on lesbian, gay and bisexual Americans — but asking questions on gender identity is still a long way off.

That’s partly because there is disagreement about what it means to be transgender, and because of some people’s reluctance to identify themselves that way.

Take John, for example. John wrote to me a few weeks ago in hopes of having a question answered in my “Dear Mona” column, in which I put readers’ experiences in statistical context:

Ok. This will sound strange. I’m a tall, white, well-built man with a law degree and a six-figure job (please, on the off chance you print this, hide my identifying info). But, somehow, despite success and career, I really want just one thing I’ll never have. I wish I was female.

When I wrote back, John expressed shock about having written to me in the first place. “Given the time stamp, I was likely extremely drunk. … This is a deeply guarded secret and one that I haven’t shared with anyone beyond therapists and an unanswered email to Dan Savage’s column ten or so years ago.”

John’s place in the transgender community isn’t clear. If being transgender is just about behavior, then John isn’t included — John was born with male genitalia and lives daily life as a man. But if it’s about identity, individuals are transgender if they identify with a different gender than the one they were assigned at birth. By that definition, John would be transgender regardless of behavior.

GLAAD, an advocacy group that seeks to educate the media about the LGBT community, includes both identity and behavior in its definition:

Transgender: An umbrella term (adj.) for people whose gender identity and/or gender expression differs from the sex they were assigned at birth. The term may include but is not limited to: transsexuals, cross-dressers and other gender-variant people.

Such a broad definition could also be problematic. According to Logan Casey, a political science student at the University of Michigan, it could lead to transgender identities being dismissed as “just a choice.” Casey, who publicly identifies as a trans man, believes that could undermine support for transgender rights.

John’s message highlighted another obstacle to counting members of the transgender community, one that would persist even if a consensus were reached on definition.

John told me: “With anyone that I interact with in day to day life, when asked, I would immediately identify as male. The question about anonymous surveys is different. I almost always choose female unless someone is in the room with me. I would not identify with the trans label.”

That poses a problem that can’t be fixed by simply adding a “transgender” box beneath the “male” and “female” ones on surveys. And others feel similarly about surveys. Individuals who have undergone a sex reassignment may identify as cisgender (i.e. not transgender), stating, for example, “I am female” rather than “I am a trans female.”

The National Transgender Discrimination Survey, conducted in 2011 by the National Gay and Lesbian Task Force and the National Center for Transgender Equality, sheds light on why some people resist the transgender label. By reaching out to online trans forums and community organizations, the survey collected data from 6,450 individuals with a multiplicity of trans identities. Seventy-one percent said they hid their gender or gender transition to avoid discrimination and 57 percent said they were delaying their gender transition for the same reason.

Discrimination doesn’t just produce a reluctance to be counted; it can also create an institutional reluctance to count transgender people. Some survey writers are concerned that questions about gender identity won’t be received well by respondents.

Larry Bye, a senior fellow in public health research at the National Opinion Research Center at the University of Chicago, helped to formulate the California study on LGBT health that Gary Gates used to estimate that 0.3 percent of the population is transgender. While Gates and Bye advocate for national surveys to include gender identity, Bye cautioned that there would be “pushback.”

“The concern is that people would be freaked out if they were asked the question and that it would harm the study,” he said. “That’s the basis of the resistance — it was the same for sexual-orientation questions.”

Gates offered a way of asking about gender identity that he thinks might work: “First you ask about what sex is on your birth certificate. Then later in the survey you ask, ‘What is your gender?’ The idea is if those are different, then you’ll see it. You’re not relying on them to specifically identify as transgender.”

Previous studies have taken a different approach. For example, a survey by the Massachusetts Department of Public Health was more direct: It provided a definition of transgender before asking respondents, “Do you consider yourself to be transgender?” (About 0.5 percent of respondents said yes.)

Wording matters. It doesn’t just affect a person’s willingness to check the box and be counted — it also highlights the existence of those identities, Kerith Conron said. Perhaps if we weren’t so regularly confronted with a simple choice — “Are you male or female?” — our thinking about gender wouldn’t be so binary.

Given the challenges of going beyond the “male/female” survey option, it’s easy to see why it’s tempting to shelve the transgender question. But leaving a minority group uncounted isn’t acceptable to Gates — he described it as “demographic malpractice.” Having seen the hard-fought gains on sexual orientation statistics, though, he has hope that gender identity will make it into mainstream surveys.

“It’s going to be a long time until we have better data,” he said. “It’s going to be a tough battle … but it’s a worthy cause.”