[EM] STV - the transferrable part is OK (fair), the sequential round elimination is not

[Juho]

I agree with Raph Frank in that most EM activists probably have  
different opinions on IRV (for single winner elections) and STV (for  
multi-winner elections). Technically many of their properties are  
still the same but the final impact and nature of these elections  
(single winner vs. PR multi-winner) are quite different, and therefore  
one may not expect that people that promote IRV would promote STV and  
the other way around.

I agree that traditional closed and open lists allow more candidates  
to run than STV. They offer also a very simple and summable counting  
process. (I believe you wanted to see such properties.) But also STV  
offers full PR (with some small rounding errors that include some  
(unwanted) IRV style decisions on which candidates will get a seat),  
and it may well be the method of choice if one wants to maximize the  
ability of the voters to express their opinions (that may deviate from  
the existing party structure) and to provide proportionality also  
within the parties.

You mentioned also the possibility that candidates would determine  
their own preference (/vote inheritance) order. That would keep the  
ballots simple and summable (also in the more complex case where  
voters give two candidate names, and candidate given inheritance order  
could be used after that).

In addition to these options I'd like to mention the tree based method  
that lies somewhere between candidate given preference lists and open  
list based methods. Votes are still simple (just name one candidate).  
Tree structure allows also multiple voter opinions to be taken into  
account (not just party affiliation) and offers at that level also  
party internal proportionality. (One could have e.g. green  
conservatives as well as conservative greens in the tree structure.)  
Trees differ from the candidate given preference lists in that only  
groupings are named (not full list of individual candidates) (derived  
from the tree structure) and in that the end part of the inheritance  
order is the same for all members of each grouping.

One more argument in favour of trees is that in such structures the  
priorities of the candidates will be very clear to the voters and  
therefore the voters as well as elected representatives will know very  
well what the representatives are expected to promote. In some sense  
that gives the voters more power to determine the resulting political  
balance (e.g. if all parties have a pro-xyz grouping available). STV  
gives more freedom to the voters in expressing different vote  
inheritance orders and more fine grained proportionality within the  
parties/groupings. I'd say there are different needs and different  
traditions (including the ones related to the number of candidates,  
summability, need to protect against fraud etc.) and therefore  
different methods may be the best for different needs.

(PR makes sense in general but I wouldn't deny people the right to  
achieve the political balance using two-party systems if they so want.)

Juho



On Oct 31, 2009, at 6:17 PM, Kathy Dopp wrote:

> Ralph,
>
> I believe that you misunderstood what I was saying below. It is the
> relative *number* of candidates who run for office relative to the
> number of the voters they represent compared to the same ratio for all
> other candidates that determines whether or not STV achieves
> proportional representation. I.e. STV is subject to vote splitting or
> insufficient candidates running to represent any group of voters.
>
> STV has all the same flaws of IRV and is hence unsuitable for use in
> any elections. Its flaws far outweigh its benefits, esp given the
> existence of methods that achieve proportional representation more
> reliably and without causing all the other problems that STV causes.
>
> Kathy
>
>>
>>> 3. STV does *not* achieve proportional representation at all unless
>>> there is no vote splitting and just the right number of candidates  
>>> run
>>> who support each group's interests. I.e. the success of methods like
>>> STV to achieve proportional representation rest in the unlikely
>>> assumption that just the right proportion of candidates run (or more
>>> precisely an equal proportion of candidates run) in proportion to  
>>> the
>>> number of voters in each separate group.  This is just simple
>>> mathematical fact.
>>
>> Generally it does achieve reasonable proportional representation.
>> Parties might get less than proportional in one constituency and more
>> than proportionality in another, due to randomness.
>>
>> However, the smaller the constituencies the bigger the "seat bonus"
>> given to larger parties.
>>
>> Again, the more seats per constituency, the better, as that gives
>> better proportionality and makes it easier for smaller parties to get
>> seats.
>>
>
> -- 
>
> Kathy Dopp
>
> Town of Colonie, NY 12304
> phone 518-952-4030
> cell 518-505-0220
>
> http://utahcountvotes.org
> http://electionmathematics.org
> http://kathydopp.com/serendipity/
>
> Realities Mar Instant Runoff Voting - 18 Flaws and 4 Benefits
> http://electionmathematics.org/ucvAnalysis/US/RCV-IRV/InstantRunoffVotingFlaws.pdf
>
> Voters Have Reason to Worry
> http://utahcountvotes.org/UT/UtahCountVotes-ThadHall-Response.pdf
>
> Checking election outcome accuracy --- Post-election audit sampling
> http://electionmathematics.org/em-audits/US/PEAuditSamplingMethods.pdf
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