Homework fails another research study

I'm still working to get to the full paper (abstract here), but if the Maltese, Tai, Fan paper says what Alfie Kohn summarizes for Huffington Post, at best we are wasting a whole lot of kids' time:

But it was grades, not tests, that Maltese and his colleagues really cared about. They were proud of having looked at transcript data in order to figure out "the exact grade a student received in each class [that he or she] completed" so they could compare that to how much homework the student did. Previous research has looked only at students' overall grade-point averages.
And the result of this fine-tuned investigation? There was no relationship whatsoever between time spent on homework and course grade, and "no substantive difference in grades between students who complete homework and those who do not."
This result clearly caught the researchers off-guard. Frankly, it surprised me, too. When you measure "achievement" in terms of grades, you expect to see a positive result -- not because homework is academically beneficial but because the same teacher who gives the assignments evaluates the students who complete them, and the final grade is often based at least partly on whether, and to what extent, students did the homework. Even if homework were a complete waste of time, how could it not be positively related to course grades?
And yet it wasn't. Again. Even in high school. Even in math. The study zeroed in on specific course grades, which represents a methodological improvement, and the moral may be: The better the research, the less likely one is to find any benefits from homework.

We've got an item on this one in subcommittee.