[maemo-community] STV voting strategy

From: Dave Neary dneary at maemo.org
Date: Fri Mar 20 15:47:01 EET 2009

Benson Mitchell wrote:
> But the issue here, to me, is that  fractional transfer may be _hard_
> to verify, but it's always verifiable. In random transfer, some
> elections will always turn out the same way, and these are easy to
> verify. But some elections will involve some close call that depends
> on the random choice. In these elections, the results with fractional
> transfer are _impossible_ to verify. There's always the possibility
> that the "random" selection was cherry-picked to get the desired
> outcome. For this reason, I greatly prefer the fractional transfer.

Good argument. We don't have observers looking over the shoulder of
counters here like there are in Ireland (and even there they can't look
over the shoulders of the computers doing electronic counting).

> As a curiosity, you may be interested to know that under a oneliner
> pairwise system (simply counting who has the most pairwise winning
> ballots against all other candidates), this election's top 3 were
> predicted correctly, and 1 of the other two predicted winners was also
> an actual winner. (I published these results on IRC last night,
> labelling the top 3 as my predictions, and the others as bogus...)
> Algorithm in sh, grep, wc, and dc:
> $ for i in 1 2 3 4 5 6 7 8 9; do for j in 1 2 3 4 5 6 7 8 9; do grep
> $i.\*$j.\*0$ ./election.blt|wc -l; done; echo ++++++++p;done|dc

Interesting indeed. What it doesn't measure is the number of times $i
appeared on the ballot and $j didn't appear at all, which would also be
a pairwise win for $i. You also give a big advantage to 1, since all of
the voting lines start with 1 :)

$ for i in 1 2 3 4 5 6 7 8 9; do for j in 1 2 3 4 5 6 7 8 9; do
  grep "^1.*"$i".*"$j".*0$" ./election.blt|wc -l;
  grep "^1[^"$j"]*"$i"[^"$j"]*0$" ./election.blt|wc -l;
done; echo +++++++++++++++++p;done|dc

That gives me results which differ both from the official results *and*
from your results in the last 2 positions.

Whatever way we run it, one thing is clear - it was a close election,
and sjgadsby got a lot of votes in the lower preferences, but not so
many first preferences to balance it out.


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Email: dneary at maemo.org
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