I was not dismissing it as simply a mix-up in the parameter settings.

As I noted, the same software (apparently) was used in Burlington, VT
two months ago for a single seat IRV election. There were no
parameters related to quotas and surpluses, not because they used a
different STV algorithm, but because they used the "Intstant Runoff
Voting" rather than the "Choice Voting" algorithm.

That is, the problem in Aspen was NOT one of setting the wrong
parameters for handling surpluses. It was one of setting the election
to be conducted as an STV election, rather than an IRV election. The
program provided an entirely different designations for an "Instant
Runoff Voting" and a "Choice Election". It may or may not have used
an entirely different algorithm, because this is not necessary, and
the round by round presentation of results is the same.

The problem was not necessarily obvious in Aspen. After all, the news
release that you referenced was issued 3 weeks after the election, and
the (updated) election results at http://www.aspenpitkin.com/depts/38/
are less than transparent.

The file "May 2009 Election Results" has been updated with the
corrected results (eg they are not the same as after the election).

The file "2009 Aspen Mayor Official Instant Runoff Tally" has the
erroneous result.

The file "Manual Verification of IRV" has the correct result. It does
not appear that this last file was produced by the City of Aspen. It
does apparently include the actual ballot preferences.

The zeroing out of the 2nd place candidate's total in the city council
races was ignored in the summary of the final results as essentially
superfluous.

That is, the results were shown as 1233:910 and 1073:1030 rather than
1273:0 and 1273:0 as shown in the tally.

And as I noted, in the mayoral race, the "quota" was not reached until
93% of the 3rd-placed candidate's votes were distributed. In this
case the result was shown as 1273:1140 and not 1273:0.

>Cambridge MA transfers surpluses only of first preference votes. Their version
of STV-PR (uniquely, I think) prevents surpluses from arising at subsequent
stages (rounds) and so there is no provision in those rules for dealing with
consequential surpluses.

There is a different way of understanding this. Cambridge transfers
votes one by one. This could be considered simply a more granular
version of the practice under ERS rules or NI rules of transferring
parcels of ballots with unique transfer values separately. IIUC, if
the distribution of a parcel at one transfer value causes a candidate
to reach quota, then votes from the parcels with a lesser transfer
value are not transfered to the newly elected candidate.

In Cambridge, there are effectively instantaneuous surpluses of one
that are immediately dealt with, either by transferring to the next
continuing preference; or if there are no more continuing preferences,
by dislodging an earlier transfer from the stack of votes.

>Cambridge MA is not alone in transferring all transferable votes, even after
the required number of winners has been identified.
>This is done in the manually counted STV-PR elections to the Dáil Éireann
because the rules on refunding candidates' money deposits
>are based on the proportion of the votes each candidate has AFTER all votes
have been transferred. This adds otherwise unnecessary
>rounds (stages) to the count.

Isn't this more commonly done at earlier stages where consolidated
exclusions of trailing candidates is avoided in cases where a
candidate might reach the sub-quota (1/4 of a full quota?) to save his
deposit. At the end stages, the continuing candidates usually have a
fairly substantial share of a quota.


On Sat, 30 May 2009 12:24:27 +0100, "James Gilmour"
<jgilmour@...> wrote:

>These observations are very interesting but the incident in Aspen cannot be
dismissed simply as a mix-up in the parameter setting.
>It is irresponsible (criminally irresponsible ?) for any election official to
authorise the use in public elections of any software
>that has not been shown (and certified ?) to comply 100% with the Election
Rules specified for that particular election.
>
>The lack of real understanding of STV (both as IRV in single-seat elections and
as STV-PR or RCV in multi-seat elections) is part of
>the problem. This is compounded by some of the program writers who develop a
program fro one particular STV election and think it
>can be used for STV elections elsewhere without fully understanding the subtle
but vital differences in the local election rules.
>(I have so far identified seven different ways of transferring surpluses.)
>
>If the Aspen incident was indeed the result of a mistake in the parameter
setting for that particular program , it raises a very
>interesting question about the use of such multi-option software to count
ballots in public elections. In this case, it appears to
>have been a mistake, an accidental incorrect setting, and the consequences of
the wrong setting were obvious in the results. But
>what is to prevent an election technician with the relevant knowledge from
deliberately setting some parameters incorrectly in the
>hope of biasing the result in favour of some candidate or party and in a subtle
way that would not be so obvious in the results?
>Ideally, the unwanted multi-option code should have been removed from the
program before certification or the multi-option
>parameters should have been locked down before certification so that they could
not subsequently be changed, either accidentally or
>intentionally.
>
>The only way to check that any computerised count has been done correctly,
fully in accordance with the relevant Election Rules, is
>to publish all the ballot data (as preference profiles) after the election so
that anyone can run the data through any other program
>that matches the relevant Election Rules.
>
>I would also suggest that some of these problem would be avoided if the
programs for single-seat STV (IRV) counts used a completely
>different algorithm from that for STV-PR, based on the simplified rules for
single-seat STV (= IRV, = Alternative Vote) that I
>codified for the Electoral Reform Society in 1978. These Rules, with very
slightly modified wording, can be found on the ERS
>website at:
> http://www.electoral-reform.org.uk/article.php?id=116
>Importantly, in these single-seat rules there is no calculation of a quota
(threshold) and no reference to "surplus" as there cannot
>be any.
--
Jim Riley