[EM] Fw: borda count
Steve Eppley
seppley at alumni.caltech.edu
Sat Nov 6 11:39:30 PST 2004
Hi,
Stephane R wrote:
> To the possible exception of how one counts truncated ballots...
> If you assume all ballots are full rankings Steve is right.
> However, some treatments proposed on this list for truncated
> ballots could produce different winners in case of equal
> ranks or partial rankings...
> I promote treatment of such cases that end up with the
> same total points as a fully ranked ballot. With any ballot
> producing the same number of points, Steve is right.
I assume Stephane is right. I don't know all the Borda
variants that've been proposed on this list, but the
handling of non-strict orderings can make a difference.
I don't know if the Duc de Borda considered the possibility
of non-strict orderings. If my memory is correct, his
formula was to award to each candidate the number of
candidates the voter ranked below it. (This is like
3-2-1-0 except for candidates ranked as equals.)
Given N candidates, a candidate ranked uniquely top
would receive N-1 points from that ballot. Taking
the formula literally, if two candidates are ranked
equal at the top they would each receive N-2 points.
John Duggan taught a different definition of the Borda
count that he prefers: Each candidate scores the number
of candidates ranked below it minus the number ranked over
it. This variation elects the same as the variation that
awards to each candidate the number of candidates ranked
below it plus half the number ranked equal to it.
--Steve
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