We independently track political betting odds offered by individuals on the Betfair exchange in order to visualise trends, expose live odds via an API, and build the web's largest archive of historical political betting odds.

Betfair is immensely impressive; comfortably the world's most traded and most liquid betting exchange. But they have historically been poor at visualising market odds over time in an accessible format, and as far as we know they do not keep or make available historical betting odds for later analysis.

In the growing sphere of political betting, we think there is a strong case to do both of these things. So once a minute, we fetch and store the average of back & lay prices and volume information that Betfair publish publicly relating to a range political events.

Bets on political events matched on the Betfair exchange are interesting because, via their price, they represent at any given moment a real-money-backed crowd consensus on the likelihood of a given outcome.

Unlike financial metrics (such as currencies) that may also track major political events to some extent, betting markets are clear and single-issue.

Betting markets are certainly not perfect predictors of events. There is however some evidence to suggest that betting markets are on average good predictors of political events.