Sure, but generally because the aggregated polls were systematically off. You may be thinking of other examples, but the 2016 US presidential election really wa

Sure, but generally because the aggregated polls were systematically off. You may be thinking of other examples, but the 2016 US presidential election really wasn't that bad of a look for 538, they had Trump at reasonable odds going into election night. It's not like he was at 5%, 538 pegged him at 1/3 odds as polls opened if I remember correctly.