You are using the techical description of "efficient markets" right? (i.e. perfectly accurate odds). Of course by this standard you are bound to be correct. However I'm sure you realized that by participating in and 'beating' the market you are increasing its accuracy.
The important question is 'how useful or accurate are these markets compared to anything else?'. I'd challenge you to find a more accurate predictive indicator that is publicly available (even if not for free).
fivethirtyeight.com may have a more reliable method. Time will tell. An aggregate of polls with solid math applied to it might just win by having more data.
Now, if there were a US-legal prediction market, that would be something.
I think it is unlikely that fivethirtyeight.com would be more reliable. The human minds are still more subtle than statistical methods alone. However even if 538 did prove more accurate its results would soon be incorporated into the market by betters. The reverse is not so likely to occur.
> Now, if there were a US-legal prediction market, that would be something.
You would have to think that involving US citizens would improve the market's accuracy. It's ironic that US-citizens can't bet.
The important question is 'how useful or accurate are these markets compared to anything else?'. I'd challenge you to find a more accurate predictive indicator that is publicly available (even if not for free).