I know I must have brought this up before, but I still think it's a good idea to let people leave comments about conference sessions and speakers on the meeting's Web site, in addition to just the evaluation. And now there's some proof in the form of a paper called â€The Availability Heuristic in the Classroom: How Soliciting More Criticism Can Boost Your Course Ratingsâ€ by Craig R. Fox, UCLA Anderson School and Department of Psychology (link goes to Guy Kawasaki's blog, where you can download the paper as a pdf). Guy says:
Go ahead and ask them for more input and see what happens. I'd be curious to know how this plays out in a conference setting, as opposed to a university course, but I'm guessing the end result might be similar.