Truncated preferences ok for Condorcet (was Re: [EM] Ignorance)

James Gilmour jgilmour at globalnet.co.uk
Wed Mar 3 10:52:25 PST 2004


Steve Eppley wrote:
> The third explanation is a hold-over from elections that 
> tally Instant Runoff (or the proportional representation 
> version, Single Transferable Vote) by hand.  To quickly 
> tally Instant Runoff by hand: 
> 
>    Distribute the ballots into piles, each according to
>    its top-ranked candidate.  From the height of each pile,
>    you can see at a glance which pile has the fewest
>    ballots.  So, if there are more than two piles, take 
>    the shortest pile, eliminate its candidate, and
>    redistribute its ballots to other piles according to
>    their highest-ranked non-eliminated candidate. 
>    Repeatedly eliminate & redistribute the shortest pile 
>    in this way until only two piles remain and elect the
>    candidate of the taller pile.

I don't know where you found this description of IRV, but it could result in a lot more paper
shuffling than necessary.  The piles should be counted at every stage and papers transferred only so
long as necessary, ie until some one candidate has as many votes or more votes than all of those
remaining.  That is often achieved before all but two have been eliminated.
James




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