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5.2.16

Social choice and the 2016 US presidential election


Marquis de Condorcet

This is one of those "seasons" of the US political cycle, where I follow US opinion polls very closely, and I noticed a funny, little odd thing looking at some of the polls--specifically the RealClearPolitics.com polling averages (General Election head-to-head match-up polls & national party primary polls of Democrats and Republicans) and a single head-to-head match-up primary poll (with Cruz v. Trump and Rubio v. Trump, NBCNews/WSJ) not included in those averages.

On the day of the Iowa Caucus I wrote a hasty little research note on the topic, which you can download here.

But here is the gist of it, where > means "beats":

  • Clinton > Trump
  • Clinton > Sanders
  • Cruz > Clinton
  • Rubio > Clinton
  • Rubio > Sanders
  • Sanders > Cruz
  • Sanders > Trump
  • Trump > Cruz
  • Trump > Rubio

If that is correct (and we are disregarding the question of the confidence intervals of the polls), then we would seem to have three possible "cyclical majorities" (of a sort) involving all five leading contenders for the nomination of the two parties:
  • Sanders > Trump > Rubio > Sanders 
  • Rubio > Clinton > Trump > Rubio 
  • Cruz > Clinton > Sanders > Cruz 


Not Marquis de Condorcet
This is, of course, somewhat speculative and quite counter-factual, given that it is based in different "constituencies" (so to speak).  But it certainly suggests--as in the "Condorcet Paradox"--that no matter which of these five might win the US presidential election in November, there is a non-trivial possibility that that person could be beaten in a pairwise contest by at least one other candidate.




2.3.15

Vælgernes viden og uvidenhed

Politiken kan dd. fortælle på baggrund af en surveyundersøgelse blandt yngre danskere, at de adspurgte som helhed betragtet generelt ikke forstår så meget af økonomiske forhold.  Og det er endog når man spørger dem om deres privatøkonomi.

Der er desværre grund til at tro, at vælgerne ikke er klogere, når det gælder politik og andre samfundsforhold.  Tværtimod er deres viden ofte langt fra de fakta, de forsøger at tage stilling til.  Det har jeg fornylig haft to klummer om, nemlig

17.2.14

Empirical social choice - special issue of "Public Choice"

Does modern democracy produce outcomes preferred by a majority of the voters? One would think that this must be so.

But not necessarily.  Since the 1950s social scientists have been interested in those instances where there is a potential discrepancy between individual preferences and collective choices. For example, individuals are usually assumed to have "transitive" preferences; say, I like foie gras more than pasta and pasta more than shrimps--therefore we may assume that I like foie gras more than shrimps.  If I do not, then most people would find my ordering somewhat odd.

But when more than two such individual preferences over more than two alternatives are aggregated as a social choice (e.g. through a vote), we may get "intransitive" collective preferences--e.g.,

foie gras > pasta > shrimps > foie gras.

This "voting paradox"--most famously developed by Condorcet and in modern days applied by Kenneth Arrow and William H. Riker--has profound implications for how we may view not only democratic decisions but politics in general.  Alas, while thousands and thousands of studies have been made of the theoretical aspects of such phenomena, the empirical side is much less studied.

Since the late 1990s a large part of my own research agenda has been devoted to such issues (e.g., cycles in voter preferences [paper here], voting paradoxes in proportional electoral systems [gated paper here] and election inversions [gated paper here; ungated version here]).  The most recent issue of "Public Choice" is a special issue on "Empirical Social Choice", guest edited by myself and--on the occasion of the 30th anniversary of William H. Riker's seminal book "Liberalism against Populism" (1982)--devoted to empirical studies of voting paradoxes and the effects of different voting methods.


I have two papers in the special issue myself: 1) An general introduction devoted to Riker's book and its implications, as well as an overview of the contributions to the special issue ("Empirical social choice: An introduction", gated paper here; ungated version here); 2) an analysis of the 1975 government formation in Denmark ("Picking a loser?", gated paper here; ungated version here).  In the latter I argue that the process made visible a flaw in the Danish procedures: Given the preferences of the political parties and the system of "negative parliamentarism", the Danish political system ended up with what was possibly only the third ranked government alternative, one supported only by a minority in parliament.  Different procedures might well have produced what was the majority preferred outcome: A centre-right government led by Poul Hartling.

The special issue contains a number of interesting contributions by prominent political scientists and economists such as John Aldrich, Steven Brams, Josep Colomer, Keith Dougherty, Bernard Grofman, Nicholas Miller, Michael Munger, Mogens N. Pedersen, Bjørn Erik Rasch, Norman Schofield, Nic Tideman and Ad Van Deemen.