What you want from a prediction market is not the chance of a given candidate winning the presidency, but the chance of a given candidate winning the presidency if they win the nomination. So, for each of the listed democratic candidates, take Predictit’s probability that they win the presidency and divide that by Predictit’s probability that they win the nomination: P[presidency | nomination] = P[presidency & nomination] / P[nomination] = P[presidency]/P[nomination], ignoring the chance that someone gets elected president without winning the nomination.
Just looking at the most recently traded prices, I see:
Harris: .19/.24 = .79
Biden: .12/.16 = .75
Warren: .07/.10 = .70
Sanders: .10/.15 = .67
Brown: .07/.11 = .64
O’Rourke: .08/.13 = .62
Booker: .06/.10 = .60
That said, the price spreads are ridiculously wide and the trade volume is a trickle, so the error bars on all of those implied probabilities are huge. We’ll probably get tighter estimates this time next year.
Thanks for laying that all out. It’s more helpful info out of PredictIt. Unfortunately it doesn’t appear to point to a trend about whether a more progressive/leftist candidate, or moderate/centrist candidate, would be likelier to win. If I had to guess, I’d say Biden and Harris are more moderate candidates...? But that’s not based on much, and like you said the range on all those estimates is still huge.
What you want from a prediction market is not the chance of a given candidate winning the presidency, but the chance of a given candidate winning the presidency if they win the nomination. So, for each of the listed democratic candidates, take Predictit’s probability that they win the presidency and divide that by Predictit’s probability that they win the nomination: P[presidency | nomination] = P[presidency & nomination] / P[nomination] = P[presidency]/P[nomination], ignoring the chance that someone gets elected president without winning the nomination.
Just looking at the most recently traded prices, I see:
Harris: .19/.24 = .79
Biden: .12/.16 = .75
Warren: .07/.10 = .70
Sanders: .10/.15 = .67
Brown: .07/.11 = .64
O’Rourke: .08/.13 = .62
Booker: .06/.10 = .60
That said, the price spreads are ridiculously wide and the trade volume is a trickle, so the error bars on all of those implied probabilities are huge. We’ll probably get tighter estimates this time next year.
Thanks for laying that all out. It’s more helpful info out of PredictIt. Unfortunately it doesn’t appear to point to a trend about whether a more progressive/leftist candidate, or moderate/centrist candidate, would be likelier to win. If I had to guess, I’d say Biden and Harris are more moderate candidates...? But that’s not based on much, and like you said the range on all those estimates is still huge.