Archive for February, 2012

Estimating the US Presidential election result based on recent opinion poll levels

February 23, 2012

Opinion polls ahead of November’s presidential election contest in the United States of America have generally tended to be relatively favourable in recent weeks for Barack Obama with these polls putting him a few per cent ahead in head-to-head contests with his most likely opponents, Mitt Romney and Rick Santorum, and holding a significant poll lead over the other candidates for the Republican Party nomination. But it will not be the candidate who wins the most votes that wins this election (as proved to be the case in the controversial 2000 contest) but the candidate who wins the most Electoral College votes. Each of the states in the USA (and the District of Columbia) have a certain number of Electoral College votes attached to them, with this number based on the number of Senators (always two) and members of the House of Congress (a function of a state’s population level, but each state has at least one representative) representing the state. As such, the number of Electoral College votes assigned to different states is shaped somewhat by states’ population levels but with a bias towards the states with the smaller population levels as they will always be guaranteed three Electoral College votes

The proportion of Electoral College votes won by candidates in the presidential election does not measure up exactly to their actual share of the first preference vote. The disproportional nature of this electoral system is down to the fact that all the Electoral College votes on offer in a state are assigned to the candidate who wins the most votes in that state on a “winner takes all” basis. In some cases the level of difference/bias can be quite significant where winning candidates’ share of the Electoral College votes have been seen to far exceed their share of the popular vote in a number of past contests – ironically the 2000 contest was probably one of the most proportional contests in this regard. In order to assess how support levels evident in opinion polls might translate into Electoral College vote numbers, I attempt to estimate what the candidates’ first preference votes would be in the different states, assuming similar (proportional) change in party vote shares in all states along the lines of the constituency-level analysis of opinion polls model as covered in a number of posts on the website. (more…)