But more recently, prediction markets have developed an odd sort of problem. There seems to be a feedback mechanism now whereby the betting-market odds reify themselves.

What do we mean by that? In the case of Brexit, it goes like this: Different surveys give different results, and we all know not to trust the polls, which have notoriously failed in... See more

adly, Manifold does not produce particularly good predictions. In last year’s ACX contest, it performed worse than simply averaging predictions from the same number of people who took part in each market. Their calibration, while good by human standards, has a clear systematic bias towards predicting things will happen when they don’t (Yes bias).... See more

The bottom line for me is that forecasts can’t be right often enough to be worthwhile.