Open Access
Translator Disclaimer
November 2002 The mathematics and statistics of voting power
Andrew Gelman, Jonathan N. Katz, Francis Tuerlinckx
Statist. Sci. 17(4): 420-435 (November 2002). DOI: 10.1214/ss/1049993201


In an election, voting power---the probability that a single vote is decisive---is affected by the rule for aggregating votes into a single outcome. Voting power is important for studying political representation, fairness and strategy, and has been much discussed in political science. Although power indexes are often considered as mathematical definitions, they ultimately depend on statistical models of voting. Mathematical calculations of voting power usually have been performed under the model that votes are decided by coin flips. This simple model has interesting implications for weighted elections, two-stage elections (such as the U.S. Electoral College) and coalition structures. We discuss empirical failings of the coin-flip model of voting and consider, first, the implications for voting power and, second, ways in which votes could be modeled more realistically. Under the random voting model, the standard deviation of the average of n votes is proportional to $1/\sqrt{n}$, but under more general models, this variance can have the form $cn^{-\alpha}$ or $\sqrt{a-b\log n}$. Voting power calculations under more realistic models present research challenges in modeling and computation.


Download Citation

Andrew Gelman. Jonathan N. Katz. Francis Tuerlinckx. "The mathematics and statistics of voting power." Statist. Sci. 17 (4) 420 - 435, November 2002.


Published: November 2002
First available in Project Euclid: 10 April 2003

zbMATH: 1062.91019
MathSciNet: MR1977137
Digital Object Identifier: 10.1214/ss/1049993201

Rights: Copyright © 2002 Institute of Mathematical Statistics


Vol.17 • No. 4 • November 2002
Back to Top