Public opinion polls on the eve of the second round of the French presidential election suggest that incumbent Nicolas Sarkozy is heading for near certain defeat. For supporters of the president looking for a glimmer of hope, Bertand Lemennicier, professor of economics in Faculty of Law of the University of Paris Sorbonne, Pantheon-Assas, has written a paper using spatial models of voting to predict the outcome of the 2012 French Presidential Election, which he has kindly made available to The Monkey Cage here. As the report is in French, he has also sent along an English language summary which is available here.
The model relies on three assumptions:
- that each candidate can be located on a left–right axis;
- that, in order to win, candidates seek to find a set of voters ideologically proximate to them to whom they can appeal;
- that, ceteris paribus, electors vote for their preferred candidate (the candidate closest to them ideologically) in the first round of the French presidential elections
With these assumptions in hand, the following approach is adopted:
We predict that the winner will be the candidate the closest to the overall median voter in terms of the % percentage of vote the candidate needs to capture on his right (if he is on the left) or on his left (if he is on the right). By using the historical records of French Presidential elections we can estimate the percentage of votes at the second round in function to the distance to the overall median voter. Two months before the election we use opinion polls to have an idea of the bimodal distribution of votes and we calculate how far is the candidate from the left from the overall median voter of the distribution of votes.
[h/t to Bernie Grofman]