[EM] Asset Voting vs STV
Abd ul-Rahman Lomax
abd at lomaxdesign.com
Tue Apr 24 20:21:38 PDT 2007
At 08:33 PM 4/24/2007, Jonathan Lundell wrote:
>On Apr 20, 2007, at 7:41 AM, Abd ul-Rahman Lomax wrote:
>
>>I'm just taking the opportunity to note the similarity between
>>multiwinner STV and Asset Voting. With multiwinner STV the vote
>>transfers are guided by user rankings, and in Asset Voting, by,
>>essentially, a proxy chosen by the voter. They are really the same
>>method, differing only in who provides the tranfer information.
>
>If I understand Asset Voting (and I may not), there's more to it than
>that. An important aspect of STV (without which is loses later-no-
>help/harm, a critically important property, to my mind) is that, in
>any given round, only the current top choice on each ballot is
>considered.
Well, that's a *little* more. I was noting similarity, not identity!
With Asset Voting, the transfer information is provided by a proxy.
(We often assume that this person is a candidate, but not
necessarily. Indeed, with single-winner Asset there are some reasons
why we might prohibit candidates from serving as proxies. But that's
another story. I've assumed total freedom both in registration as
candidates and in choosing what candidate(s) to name.)
With STV, the vote transfers are determined by a ranked list, so that
the top name is used unless that candidate is eliminated, then the
next name, etc. The voter provides the transfer information, which is
used specifically and rigidly. It's the rigidity that is the problem.
As I've noted, the problem is not generally serious with multiwinner
STV, it seems, but it *is* a limitation and affects the ability of
STV to maximize voter freedom in choosing representatives.
>One could, of course, allow a voter to fill out a truncated STV
>ballot by indicating somehow that the remainder of the ballot should
>follow an ordering specified by some third party (it could be my
>favorite candidate, or my party, or any other appropriately
>registered preference ordering). Such a variation would preserve
>later-no-help/harm, but allow the voter to defer to the judgement of
>a third party.
This kind of hybridization is often possible with methods. For
example, it is generally considered that Range Voting does not
satisfy the Majority Criterion. However, if we add a top-two runoff,
where the Range winner and the Condorcet winner, if there is any that
differs from the Range winner, face each other in a choose-one
election, the combination satisfies the Majority Criterion. That is,
if the majority has a preference, and maintains that preference in
the face of a differing Range winner, the majority cannot fail to
prevail. This, actually, I personally prefer to Range alone. But if
we must have a single step under all conditions -- a serious
limitation in my view, and a foolish one -- then I refer Range. It
will almost always choose a Condorcet winner.
(Asset is kind of a trick, it is not an "election method" as it is
sometimes defined: deterministic, using a single poll as the only
input. It is, rather, a hybrid itself, between a simple
meet-the-quota-and-you-are-elected method and a deliberative,
negotiated process.)
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