and as far as I know they are the best mechanism to predict the outcome of an election. It's an honest opinion since they are betting their own money independently of their personal preferences.
Are you suggesting that people will make bets in a purely rational way, and only by considering (in this case) what they know about the UK election? I suggest that plenty of people will either bet emotionally, choosing the option they prefer, or psuedo-rationally (i.e. reasoning poorly). I expect many will also use the odds provided on the website to guide their choices.
Possibly not a site like this. But predictions made by bookmakers should in theory be accurate, since the bookmaker has a financial incentive to make them accurate and no political incentive to misrepresent them.
Have you looked at the site? What should I bet against? There are a lot of choices :-)
I don't imagine a clear divide between 'rational' and 'irrational' betting (for want of a better description), I'm just saying that I would expect there to be a lot of both going on.
If you're wondering why I believe this, the book 'Predictably Irrational' by Dan Ariely springs to mind as a good read about the subject. Also 'The Tiger That Isn't' (Michael Blastland/Andrew Dilnot), not about human rationality as such but rather, how easily we can be foxed by information depending upon how it is presented to us (in the context of 'reasoning poorly' about the election).
