Electoral Systems Evaluations of electoral systems Fairness Proportionality

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Electoral Systems

Electoral Systems

Evaluations of electoral systems • Fairness = Proportionality? • California statewide vote for seats

Evaluations of electoral systems • Fairness = Proportionality? • California statewide vote for seats in the House of Representatives: 43% R 54% D • California distribution of seats in the House of Representatives: 38% R 62% D

Evaluations of electoral systems • Level of satisfaction? Number of losers? • Fairness =

Evaluations of electoral systems • Level of satisfaction? Number of losers? • Fairness = Proportionality? • Representation • Simplicity

Consequences of Electoral Systems

Consequences of Electoral Systems

How do electoral systems affect the behavior of candidates and voters? • Party systems

How do electoral systems affect the behavior of candidates and voters? • Party systems • “Duverger’s Law”: The more proportional the system, the greater the number of “effective” political parties there will be.

Why Duverger’s Law • Mechanically • Psychologically (candidates) • Psychologically (voters)

Why Duverger’s Law • Mechanically • Psychologically (candidates) • Psychologically (voters)

Evidence for Duverger’s Law Electoral formula “Effective” # of political parties USA Plurality 1.

Evidence for Duverger’s Law Electoral formula “Effective” # of political parties USA Plurality 1. 95 Australia Majoritarian 2. 5 Nepal Plurality 2. 4 Canada Plurality 2. 7 UK Plurality 2. 2 Belgium D’Hondt 8. 54 Netherlands D’Hondt 5. 14 Austria LR Hare 3. 54 Germany LR-Hare 3. 31

Evidence for Duverger’s Law

Evidence for Duverger’s Law

How do electoral systems affect the behavior of candidates and voters? • Party systems

How do electoral systems affect the behavior of candidates and voters? • Party systems • Party organization • Election campaigns

The American System • • • Seats not allocated proportionally Constituency based representation Simple

The American System • • • Seats not allocated proportionally Constituency based representation Simple ballot choices Two large coalitional parties Decentralized campaigns

Median Voter Theorem • Assumptions: • • Single dimensional issue space Pairwise vote Voters

Median Voter Theorem • Assumptions: • • Single dimensional issue space Pairwise vote Voters always vote (no abstentions) Voters have one unique preferred position Voters’ preferences “single peaked” Parties/candidates maximize chances of winning Preferences are normally distributed in electorate

Median Voter Theorem • If all voters vote and their preferences are single-peaked and

Median Voter Theorem • If all voters vote and their preferences are single-peaked and on a single dimension, then the median ideal preference can defeat all other positions in a pairwise vote.