2016 President - Democratic Nomination
Market data: Step 1: construct prices from the back, lay, and last transaction odds, in the Betfair/PredictIt order book. We take the average of the cheapest cost to buy a marginal share and the highest price to sell a marginal share, unless the differential is too large or does not exist. Step 2: correct for historical bias and increased uncertainty in constructed prices near $0 or $1. We raise all of the constructed prices to a pre-set value depending on the domain. Step 3: normalized to equal 100% for any mutually exclusive set of outcomes.
Polling data: Curtesy of HuffPost's Pollster
Bookie data: Lowest price I could find to buy that contract (current on 6/19/2015 at 2:00 PM ET). Will update weekly.