DIE ZEIT, a german weekly newspaper, asked people to forecast the election results of the state election in Hamburg. 810 participated from Feb 16 to 19 on Facebook and Twitter. Below the distribution of the forecasts for each party, along with the final election results from Feb 20 (red line) and the result of a telephone survey (green line) undertaken by GMS – a commercial public opinion polling service – between Feb 15 to 17. Data source: here, here and here.
It is pretty amazing, that the crowd forecast is almost identical with the survey results from GMS. Although both failed to predict the election results with a reasonable accuracy, the experiment shows that crowd forecasting might be an interesting method to poll the population with lesser cost and almost the same accuracy as conventional polling. I am sort of surprised about the high correlation between the GMS results and the crowd forecast, since I had suspected that they diverge due to self-selection biases in the crowd forecast experiment.