The survey might or might not be biased — the bigger problem is that entire parts of it are completely useless.
In particular, given that the army that isn’t supposed to have any (openly) gay soldiers, the survey asks the troops to engage in an awful lot of speculation about the gay soldiers in their midst.
Of course, Nate says a lot more. He does a thorough job of explaining why. Definitely worth a read.
And, this just adds to the growing controversy about this survey. What the hell was DOD thinking?