There are certain failure modes that that doesn't work for. I had a group project once where none of the other three members really did much at all, not becaus

There are certain failure modes that that doesn't work for. I had a group project once where none of the other three members really did much at all, not because they were lazy but just because they weren't very competent (seriously, I spent like five hours with a member who was a software engineering major trying to help her write a few lines of C that would run on a microcontroller on the board that I designed. In the end, I just wrote all the code... I wanted to help them learn, but the amount of background knowledge they didn't have just made it impossible in the time we had). When it came to peer assessment, the way it was done was that the person being assessed would go outside, and the rest of the group assessed them and come up with a single rating. So you couldn't mark them down much really because everyone else knew that they had all done the same amount of work as that person... So we all got the highest grade in the end (not that I would have crucified them or anything though, since they were fairly willing to try).