The individual scores are based on the groups score reduced or multiplied by the individual input/learning gains. This way takes into account the individual input as well as the group learning process.
The members evaluate themselves and each other. This from of evaluation is called peer-evaluation. Peer-evaluation is often used as part of an evaluation because it stimulates a critical look at:
the group process
the group product
the personal input
So, the peer assessment is not only focused on the end product but also on the process itself and the ownership therein. The peer assessment can be included in the final score, or may be part of the online collaborative learning.