Wow that was weird...my question was answered before it was even posted!

Computers can be so funky!
My question now is, who decided their methods don't work? Is it the research that is done by somebody who sits in an office who just observes students but has very little classroom experience, parents or by reports that are done by the teachers to help track the students progress?
Yes, I meant the teacher's intent is irrelevant if what they are doing is detrimental to the student. I don't care that my kids' teachers think they are doing it for my kids' own good, if in fact, they are making my kids hate learning, and make no academic gains attributable to the homework. There was going to be more to that post, but the Disboards were acting really wonky for me earlier and posted in the middle of something.
Research is published in the peer-reviewed literature of a discipline. The research in education is done by different groups, including classroom teachers, administrators, PhD candidates and research faculty. Generally speaking, the group of subjects are divided into a control and an experimental group. The results are compared, analysed and submitted to the refereed literature. The results are distributed blindly to several people who are recognized as being authoritative in the field before (if) it is deemed valid for publication.
With social science research dealing with humans, the results are very seldom 100% conclusive, as In A Hurry mentioned. However, one can look at the preponderance of the literature to draw valid conclusions.
Education is a very funny field, in that sometimes the conclusion the authors come to is at odds with their actual data, often for personal, institutional and political reasons. That's why you have to read the actual studies to understand the findings. That's one thing I like very much about Kohn's work. He is great about finding the studies where the data says one thing, but because the researcher has his or her own agenda, and manages to make some very odd conclusions. When you get your hands on the actual literature and read it, it would be funny if it weren't so damaging. This is the case for much of the literature that makes recommendations in favor of homework. When you look at their data, it says exactly the opposite.