re: 80% of student feedback is incorrect:
As a teacher I see this in class every single day, kids wrongly explaining to others what they've done right and wrong. Especially what they've done wrong! Even if it's a subjective question the kids will authoritatively tell each other exactly how wrong they are when they might be onto something really special.
Remember my famous group work/peer review story? My son was in a group doing a math problem. He understood it and worked out the right answer; the four other kids were arguing for a different answer. He had been appointed group leader, who was supposed to give the group's answer. When called upon to give the group's answer, he gave his (correct) answer.
He was reprimanded for not giving the group's "consensus" answer. When he protested that it was wrong, he was told he should have done a better job convincing them of the rightness of his answer.
So you can see that the point of the whole exercise was far afield from the kids actually learning how to do the problem...
Peer review in my son's (3rd grade) class wass of the form, "It's got a great beat and you can dance to it, so I give it an A". Had this been managed at all by the teacher, it could have risen to the level of merely useless, but the teacher's classroom management skills needed remediation -- desperately.