|Mean of Bookies predictions for seats won in UK 2015 General Election|
|Mean of Bookies predictions showing Con+LibDem & Lab+SNP|
These values were collected by repeatedly scraping bookies websites for odds given for various bands of seats for each party, eg:
As I type this Ladbrokes is giving 7/4 odds for SNP getting 40 to 49 seats in Westminster.
Each of those odds is turned into a probability, the mean of each party/band is then amalgamated to give a number of seats which the bookies as a gestalt think each party will win.