[EM] Range Voting and Cardinal Ratings Runoff

[Forest Simmons]

> Date: Wed, 15 Dec 2004 20:30:19 -0800
> From: Brian Olson <bql at bolson.org>
> Subject: Re: [EM] Is range voting the panacea we need?


>
> Straight rating summation is vulnerable to strategic voting. Perhaps in
> this study people voted honestly because it obviously didn't matter and
> so there was no incentive to vote strategically. In a real election the
> stakes would be higher.
>
> My favorite solution is to run Instant Runoff style disqualification
> cycles over Normalized Ratings (IRNR). I believe this method is
> strategy proof and passes a handful of other desirable election method
> criterion.
>

In general, methods that proceed by sequential elimination are not 
strategy proof:

Suppose that there are only three candidates, and you think that your 
compromise C has a significantly better chance than your favorite F of 
winning against the candidate D that you dislike the most, and that there 
is a good chance that D will be one of the finalists.  Suppose further, 
that F and C both have decent chances of getting into the final round.

In this situation, you have an incentive to "bury" your favorite F, i.e. 
to try and make F lose in the first round.

This may not be too common, but it is a barrier that every third party has 
to surmount if they are to graduate from non-entity to serious contender 
status.

Labor may be short compared to nine months of gestation, but birth cannot 
happen without it.  A random sample of the nine months might give the 
impression that labor is too rare to worry about.


Similarly, before a third party can win an election it has to reach the 
stage at which this burying strategy becomes a problem, if the election 
method proceeds by sequential elimination.


For this reason Kevin came up with the "Runoff Without Elimination" idea, 
culminating in his "Gradual Approval," which I believe to be a superior 
use of Cardinal Ratings style ballots.

It doesn't suffer from the burying strategy because all candidates are 
still in the race in the last round.

A candidate with lots of success in previous rounds just gets the approval 
cutoff moved closer to her as a "reward," so losers of previous rounds 
(whether favorite or compromise or both) still have chances in the final 
round.


Forest