I haven't done much research on it but I wonder about the effectiveness of play prediction markets (manifold for example) as opposed to actual money based ones.

I haven't done much research on it but I wonder about the effectiveness of play prediction markets (manifold for example) as opposed to actual money based ones. I think a lot of smart people don't really care that much if the money is real or not. They will participate regardless because it's fun to watch the number grow, but on the other hand, making it be play money makes dumb money much more likely to happen. Perhaps a good way to go around it is to provide the market as a play market but give financial incentives to good performers at the end of the week, month, etc.