LOS ANGELES — About 9 million people in the United States identify themselves as lesbian, gay, bisexual or transgender, according to a UCLA study released Thursday.

The estimate, which translates to about 3.5 percent of adults as LGBT and 0.3 percent of adults as transgender, was created by the Williams Institute at UCLA’s School of Law and argues that any estimate of the population is difficult because there are insufficient and inconsistent national surveys.

The study culled data and methods from nine surveys conducted over the last seven years and averaged results from five of those surveys to estimate sexual orientation and results from two surveys to estimate the transgender population.

Among other findings: Of the lesbian, gay and bisexual population, bisexuals were a slightly larger group, representing 1.8 percent of the adult population compared to 1.7 percent who were lesbian or gay.

It also found an estimated 8.2 percent of Americans reported participating in same-sex sexual activity; and an estimated 11 percent held some same-sex sexual attraction, but neither group necessarily identified as lesbian, gay, bisexual or transgender.