A Geometric Model of Elections in Five Federal Democracies

Abstract In an analysis of 1,825 state or provincial election outcomes in five federal democracies the rate of decay of incumbency ( K ) serves to partition the distribution of the vote for the incumbent party, the party of the head of government, between those who win a subsequent term and those who do not. In conjunction with the mean and standard deviation of the distribution, the weighted mean of the vote in re-election and defeat is identified. The model’s predictions are generally within 2–3 percentage points of the actual outcome.