[EM] FAVS

[Juho]

On Dec 17, 2006, at 20:45 , Warren Smith wrote:
> Range Voting was recently derided (in THE NATION magazine, Dec 25,  
> page 22)
> as "a strategic mess."
> What does that mean (I wonder)?  Anyhow, the fact that range  
> satisfies FAVS
> whereas other systems do not, seems to me to make it LESS of a  
> strategic "mess,"
> not more, than other systems.   And in general Range Voting has sipler
> strtagey than almost any other system, plus provably nice
> properties under strategic voting

As a Range Voting expert and promoter you probably know its  
properties very well also yourself but here's my quick characterization.
- RV is a wonderful method for dominantly non-competitive elections  
and polls
- RV utility function is very good when compared to most alternative  
methods
- RV is very vulnerable to strategic voting
- but strategic voting is indeed simple, just vote as in Approval
- also the FAVS properties of RV make it a nice and understandable  
tool for the voters
- in competitive situations where most voters vote in Approval style  
RV may still elect the Condorcet winner with quite good probability  
(but only with probability)

RV is certainly one of my favourite methods for seeking answer to  
question which one of the clouds on the sky is the prettiest  
(assuming that we want an exact result and are not afraid of doing  
some calculations while lying on the grass). But when we move to  
competitive elections in a traditional (typically competitive)  
democratic society RV is not my first choice e.g. to electing a  
president (this kind of large public elections are my default use  
case when discussing the properties of voting methods). The reasons are:
- RV does not support the idea of "one man one vote" very well (well,  
in theory yes, but...)
=> strategic (Approval style ballot) voters may gain multiple times  
the weight of a sincere (Range style ballot) voter
=> radical voters ("the competing candidate is all bad") voters may  
have multiple times the weight of a moderate ("the competing  
candidate is not quite as good") voter
- if RV becomes in practice Approval, then the RV side is a trap for  
voters (that are competitive but) who don't know that their vote is  
more effective in Approval style
- RV "rewards" individual voters that vote strategically by giving  
them more power
- strategic voting is beneficial in practically all situations (not  
just in extreme cases and/or requiring detailed information and/or  
coordination and/or having risks of failing and/or causing damage  
instead of benefit to the voter)

In highly competitive situations one could use Approval (RV 0..1)  
instead of normal RV (=when one doesn't want to recommend the voters  
to use Range style). But if one does so, then one could also consider  
using Condorcet or other corresponding methods that have been  
designed to cope in competitive environments (like Approval does) but  
that are more expressive than Approval. My understanding is that  
Condorcet methods are seen by many experts as emerging from the need  
to recover from the known strategic vulnerabilities of RV like more  
straight forward (expressive and good utility but vulnerable) methods.

I guess these observations are quite obvious to many readers of this  
mailing list. But maybe listing them helps in developing a wording  
that would be acceptable to all. (an optimist? :-)

Juho Laatu


		
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