Ask HN: Any purely data driven public policy research think tanks?

'How can you improve, if you do not measure?'

I remember reading that quote somewhere and it has always stuck with me.

Challenge: To measure the health of the nation. (with first-principles and scientific method.)

Are there any independent non-profits out there that are involved in rigorous and expansive research on the net positive/negative outcomes of landmark legislation on the members of society (in any particular country)? Publishing pure quantitative metrics void of political bias?