[EM] Free riding

[Juho]

On Sep 1, 2008, at 1:10 , Raph Frank wrote:

> On Sun, Aug 31, 2008 at 10:18 PM, Juho <juho4880 at yahoo.co.uk> wrote:
>> It may well be the best strategy to rank A below D in the example  
>> above if A
>> will be elected almost certainly since the voter has an interest to
>> guarantee that D will be elected rather than E. D and E might be even
>> "despised" although of course the probability of finding this kind  
>> of a
>> working (insincere) strategy decreases when the utility of D goes  
>> down.
>
> I think you should rank A as high as possible but behind at least 1
> candidate who you are reasonably sure will be elected.

I didn't quite get this part of the mail. Usually candidates that are  
sure to be elected would go down in the rankings.

> As long as you rank him lower than the expected round that he will be
> elected in, there is little risk to keeping him ranked high.
>
> Also, if he isn't ranked in the first round, then you probably want to
> give him you vote early.
>
>> If looking for links to Woodall and
>> Hylland, this approach in a way tries to generalize them under one
>> framework.
>
> It probably comes down to deciding what the cost/benefits are of
> shifting him back 1 rank.
>
> A2>A1>....
>
> is just as effective as dropping A1 as long as A1 is elected in the  
> first round.
>
> Maybe candidates with strong person votes should advise voters to rank
> them second.

I'm not sure if any candidate has any direct interest to ask for  
second rankings (instead of first) (except for truly altruistic  
reasons, or maybe to benefit the party). Parties may wish this. If  
parties intentionally manage to lower the rankings of a candidate,  
then that candidate may as for "at least second rankings".

When talking about free riding we should mostly be evaluating what is  
the optimal strategy from one individual voter point of view. Vote  
management could however be called "party free riding". In that case  
the party tries to influence the actual voters in some way. This may  
be against the interests of the individual voters. If the voter  
expects his/her personal vote to some candidate of "another party" to  
become "managed" (=all personal votes consumed almost fully) then  
that voter may change his/her voting behaviour accordingly (not vote  
for that candidate or be eve more certain to vote for that  
candidate). It is also possible that a clever party that is also able  
to control its candidates is able to make the landscape such that the  
voters actually (in theory) will find it strategically wise to vote  
in the way that the party wants them to vote (e.g. to give personal  
votes to a candidate who is close to not becoming elected).

>   The only time it matters is when they fail to get
> elected in the first round, and in that case, the assumption of being
> a certainty of getting elected has failed.
>
> Also, some PR-STV methods only look at transferred-in ballots when
> working out what ballots to transfer-out.
>
> E.g.
>
> If a candidate gets
>
> 0.4: person
> 0.4: party
>
> in the first round,
>
> and then gets 0.5 quotas of additional votes in the 2nd round.
>
> The 0.4 personal votes (and the 0.4 party votes from the first round)
> are ignored when working out the transfers as only the 0.5 quotas of
> transferred-in ballots are considered.

On very wild idea would be to allow the candidate (or maybe in  
practice the party) to decide which votes to transfer. That would at  
least make vote management less interesting. To "personal voters"  
this would mean that probably their vote will be consumed in full if  
the target candidate gets elected. Maybe this is a fair enough deal  
for many of them.

Juho





		
___________________________________________________________ 
Copy addresses and emails from any email account to Yahoo! Mail - quick, easy and free. http://uk.docs.yahoo.com/trueswitch2.html