[EM] Doesn't everybody see that IRV=BORDA?

Bart Ingles bartman at netgate.net
Sat Jan 24 15:27:01 PST 2004

I'd be interested in seeing your proof, since everything else I have
seen shows them to be quite different.

40 A>B>C
25 B>C>A
35 C>B>A

Borda scores:
A=80  B=125  C=95;  B wins (= the Condorcet winner).

IRV result:
B eliminated, C wins.

FPP result:
A wins (unless C voters use obvious strategy and support B).

Approval result:
Impossible to tell from above rankings, but in general if the voters all
know that B is the likely CW, best strategy for C voters is to approve B
as well (so long as B is a tolerable ccompromise candidate).


> Paul Kislanko wrote:
> Not that that's a bad thing, necessarily, but it is true in the sense
> that any IRV winner would've won by Borda (and with less effort, I
> might add).
> IRV adjusts ballots that include the eliminated alternatives to
> transfer rankings upward when the eliminated alternatives are not last
> on specific ballots, and the iteration is continued until one
> alternative records a majority of #1 votes. The IRV process preserves
> the relative rankings of alternatives that are not eliminated in an
> iteration.
> It is easy to see that the IRV winner will be the alternative with the
> highest Borda Count in the first round of ballot-counting.
> So, if Borda is "bad", why is IRV "good" - they are the same thing
> when it comes to picking winners.
> It is fairly easy to prove that IRV always selects the Borda winner.
> Personally, I have no objection to that, but it surprises me that IRV
> advocates dislike Borda.
> J Paul Kislanko

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