Consent is given through the click-through user agreement and the data policy https://www.facebook.com/policy.php https://www.facebook.com/policy.php . It's no

Consent is given through the click-through user agreement and the data policy https://www.facebook.com/policy.php https://www.facebook.com/policy.php . It's no different, and anything more is impractical. There are literally hundreds if not thousands of tests being done simultaneously on overlapping user populations.