[EM] PR-STV with approval based elimination

[Jonathan Lundell]

On May 1, 2009, at 6:02 AM, Raph Frank wrote:

> 2009/5/1 James Gilmour <jgilmour at globalnet.co.uk>:
>> One problem with abandoning LNH is that it opens the way for  
>> strategic voting, that is, when a voter ranks the candidates in
>> some
>> order other than the sincere 'first to last' order of preference  
>> because the voter knows that some feature of the voting system will
>> enhance the changes of the real high preferences being elected if  
>> the rankings marked on the ballot are distorted in a particular
>> way.
>
> Unfortunately, strategy is often a part of methods that encourage  
> compromise.

Part of the point of PR, it seems to me, is to represent the voters,  
or groups of voters with similar views, as accurately as possible, and  
to push compromise to the resulting legislative body, where  
compromising can be worked out dynamically one decision at a time,  
with discussion and analysis.

Forcing the voters to make a rather "blind" compromise in advance  
through strategic voting may be a necessary evil for single-seat  
elections, but I don't agree with the notion that we ought to  
encourage it in a PR system.

>
> However, the suggest modification to STV doesn't actually break the
> LNH effect.  There is no disadvantage to ranking all of the
> candidates.
>
> There would be strategy for the approval ballot though.

The strategy is effectively identical in both versions, despite the  
difference in form. That is, in both your mechanisms it seems apparent  
on the face of it that a voter would not have a motivation, strategic  
or otherwise, to choose a different approval set in the two methods.