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Jameson Quinn wrote (28 March 2010):<br>
<br>
<blockquote type="cite">><i> What does "MCV" stand for?
</i>><i>
</i><br>
<br>
Ooops. I garbled your term, didn't I? It's supposed to be Majority
Choice
Approval, not Majority Choice Voting.
</blockquote>
<br>
"Majority Choice Approval" was invented and introduced a few years ago
by Forest Simmons, and I think he <br>
coined the term.<br>
<br>
For a short time I endorsed it as something simple that meets Favorite
Betrayal, the "voted 3-slot ballot version"<br>
of Majority for Solid Coalitions and Mono-raise.<br>
<br>
<blockquote type="cite">><i> Does "top-two runoffs" mean a second
trip to the polls?
</i>><i><br>
</i><br>
Yes. I regard this as an advantage. If the situation is divisive enough
to
prevent a majority choice in two rounds of approval, <br>
then a further period
of campaigning is a healthy thing. It's the only way to guarantee a
majority. (I don't think that mandating <br>
full ranking counts as a true
majority).
<br>
<br>
<i> </i>><i> How are the candidates scored to determine the top
two? Is it based on the </i><i>candidates' scores after the second <br>
> Bucklin round? ><br>
<br>
</i><i> </i>That's the simplest answer, and I'd support it. It's also
the best answer
with honest voters.
Actually, the best answer for <br>
discouraging strategy is to use the two
first-round winners. That tends to discourage strategic bullet voting,
since
expanding <br>
your second-round approval can not keep your favorite candidate
from a runoff.
</blockquote>
<br>
Unfortunately these top-two runoff versions break MCA's compliance with
Favorite Betrayal and Mono-raise.<br>
<br>
Top-rating your favourite F could cause F to displace your compromise C
in the runoff with your greater-evil E, and then F loses<br>
to E when C would have beaten E.<br>
<br>
Also, like plain Approval followed by a runoff between the two most
approved candidates, it is *very* vulnerable to "turkey-raising"<br>
Push-over strategy. Voters who are fairly confident that their
favourite can get into the final runoff have an incentive to also
approve<br>
(or top-rate, depending on the version) all the candidates they are
confident their favourite can pairwise beat in the runoff.<br>
<br>
The Push-over incentive is stronger than it is in normal TTR, because
the strategists don't have to abandon their favourite in the first<br>
round (and so taking a much greater risk, if there are too many trying
the strategy, of their favourite not getting into the final without <br>
their votes when without their strategising their favourite would have
got into the second round and won it).<br>
<br>
Also some people might object that parties that run a pair of clones
have an advantage over parties that run a single candidate.<br>
<br>
>From your (Jameson's) earlier (26 March 2010) message, I gather you
consider "likely to elect the CW" a big positive.<br>
For something simple then, why not "3-slot Condorcet//Approval"?<br>
<br>
*Voters give each candidate a Top, Middle or Bottom rating. Default
rating is Bottom. <br>
If one candidate X (based on these maybe constrained ballots)
pairwise beats all others, elect X.<br>
Otherwise, interpreting Top and Middle rating as approval, elect the
most approved candidate.*<br>
<br>
Chris Benham<br>
<br>
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