For what it's worth, I loathe this sort of thing (damning by vague questioning): "But, if a composite is full of a measure that’s biased, how accurate is it going to be?"

Well, I don't know, and you haven't told me. Is it a consistent high bias? Low? Variable? How biased? How accurate?

What you're trying to say, without accepting responsibility for actually saying it, is "It's an inaccurate composite because it's based on biased measurements." But you don't know that, or you'd say it without weasel words.