Classroom discussion forums - are they worth it?

Of note...relatively interesting, and possibly significant work related to the use of discussion in online classes.  It's always puzzled me to determine the value of discussion and this work pokes at the issue.  From Jeffrey R. Young in the Chronicle of Higher Education.  Worth a read.

What a Tech Start-Up's Data Say About What Works in Classroom Forums - Wired Campus - The Chronicle of Higher Education

Professors may want to think carefully before giving formal grades for participation in online discussions, the data suggest. When professors required a set number of discussion posts, the number of submissions was higher than in courses where professors left participation up to students. But instructors reported the highest gains in student understanding when discussion was less strictly marked.