During the progress review, how might a project manager assess the contribution of each member of the project team?

The project manager would have to ask the person which aspects of the project that person helped to work on. If the person has a particular instance in which their incite or their work helped the project as a whole, even if it was to show what not to do, that could be useful the help assess their contribution. Could also look at their over all effort, how many hours are they working, based on feed back from group members are they giving a conservative effort to help achieve the project goals. Are their deliverables getting in on time, even if not finished, is there effort being put forth toward the end goal.