Surveys may be underestimating the size of the LGBT population and the number of people biased against them, new research suggests.

According to a study conducted by Ohio State University and Boston University and published by the National Bureau of Economic Research, people are often afraid to reveal their sexuality, even on anonymous surveys.

Additionally, people who are biased against gays tend to shy away from revealing those attitudes on surveys.

“Measuring sexual orientation, behavior, and related opinions is difficult because responses are biased toward socially acceptable answers,” the researchers wrote in their study, titled The Size of the LGBT Population and the Magnitude of Anti-Gay Sentiment are Substantially Underestimated.

The researchers suggested that the findings show that “it is perceived as socially undesirable both to be open about being gay, and to be unaccepting of gay individuals.”

Researchers used two online surveys to reach their conclusions. In the first survey, people were asked to answer yes or no to the question “Do you consider yourself to be heterosexual?”

In the second survey, the question was posed as a statement – “I consider myself to be heterosexual” – and included in a list of four statements. Respondents could answer how many of the statements were true for themselves. That is, a person could answer that two of the statements were true without actually stating which were true.

Using those results, researchers estimated that as many as 8 percent of the respondents were not being truthful about their sexual orientation.

A higher percentage of people were estimated to be hiding their bias toward gay people. When asked outright, sixteen percent said that they wouldn't be happy to have an openly gay or bisexual boss, but the second survey found a much higher estimate of twenty-seven percent.