And yet, prediction markets outperform polling, and debiased prediction markets outperform debiased polling.
e.g. Rothschild, Forecasting Elections: Comparing Prediction Markets, Polls, and Their Biases, Public Opinion Quarterly, Vol. 73, No. 5 2009, pp. 895–916
My analysis finds that in the 2008 election cycle FiveThirtyEight’s debiased poll-based forecasts were, on average, slightly more accurate than Intrade’s raw prediction market-based prices. But when prediction markets are properly debiased, they are more accurate and contain more information than debiased polls; this advantage is most significant for forecasts made early in the cycle and in not-certain races (i.e., the races typically of most interest).
Furthermore, I start two prediction threads every month and the most vocal anti-prediction market people never submit an entry. You can compete head to head with my prediction market based model. Show me that prediction markets are poor predictors don’t tell me.