[EM] Re: Approval Strategy in the Three Competitive Party case.

[Russ Paielli]

Forest Simmons simmonfo-at-up.edu |EMlist| wrote:
>> From: Russ Paielli <6049awj02 at sneakemail.com>
>> Subject: Re: [EM] Rewording Strategy A (BF(1st))
> 
> 
>> Forest Simmons simmonfo-at-up.edu |EMlist| wrote:
>>
>>> Departing from Strategy A, we offer the following refinement in the same
>>> spirit:
>>>
>>> For each candidate C, if you think the winner is more likely to come
>>> from the set of candidates that are worse than C than from the set of
>>> candidates that are better than C, then approve C, else don't.
>>
> <snip>
>>
>> You've stated what is perhaps the best strategy for Approval, but how
>> effective is that strategy? Well, in some cases it may be very
>> effective, but in other cases it may not be.
>>
>> For example, what if *three* parties are equally popular? Let's take the
>> classic Democrat (D), Republican (R), and Green (G) case. Suppose they
>> are approximately equally likely to win. And suppose your own order of
>> perference is G>D>R. Who do you approve?
>>
> 
> It is very unlikely that G and R would be exactly equal in perceived 
> likelihood of winning at the same time that D's utility is exactly half 
> way between G and R.  But even if that were the case for several G>D>R 
> voters, it would not be so for the vast majority of them.

I postulated that the three parties are "equally" popular to illustrate 
a principle, but the principle certainly does not depend on exact 
equality. The principle, by the way, is that some voters will be forced 
"guess" at the best cutoff point, and they won't know if they guessed 
right until the results are in.

How far do the candidates need to be from "equally" popular to 
invalidate the principle? Well, that obviously depends on the 
uncertainty in the estimates of relative candidate support.

I recall cases before the 2004 election in which major presidential 
polls differed from each other regularly by 5 percentage points, and it 
even got to 10 points or more at one time not far before the actual 
election. And the same polling organization would sometimes have 
significant variations from week to week. Beyond that, if you examine 
the historical differences between actual election results and, say, the 
final-week polls, I think you will see that they often differ by 5 
percentage points or more. Welcome to the real world, folks.

Moreover, all of that uncertainty applies to plurality voting with two 
dominant parties. Under Approval, the uncertainties can only be greater 
-- perhaps much greater. Yes, the first Approval election (after 
switching from plurality) will accurately reveal how much support each 
minor party really has, but after that all bets are off. The very topic 
of this discussion is how voters can strategically "draw the line," so 
the real support for each party cannot be clear from the previous 
election results alone. And that would be true even if every party ran 
the same candidate as last time, but with different candidates the 
difficulty is only compounded.

To elaborate this point, how can anyone know from the previous election 
results how many G>D>R voters approved D merely as a hedge against R -- 
and therefore might not approve D this time if the pre-election polls 
look different? And how can anyone know how many voters who didn't 
approve D might do so this time if the polling results are slightly 
different? There's no way to derive that information from the previous 
election results.

Then we need to consider the dynamics of Approval voting. I don't mean 
the election-to-election dynamics that are traditionally discussed. I 
mean the dynamics of the polling leading up to an election. Imagine all 
those G>D>R voters following the polls trying to decide whether to 
approve D. Well, if G gets an uptick or R gets a downtick, that triggers 
a downtick for D. But that downtick for D triggers more dynamics with 
other voters. An uptick for D will tend to reinforce the support for D, 
which is an unstable effect, by the way. I could go on, but the point is 
that these dynamics will be extremely complex, and I doubt anyone has 
ever studied them in detail. They may be chaotic and unpredictable, like 
the stock market dynamics. And imagine how polling organizations could 
affect the results by simply fudging the final pre-election polls a bit.

When you add up all the uncertainties and ultra-complex dynamics, the 
bottom line is that nobody really has any idea what will actually happen 
under Approval. And that is true despite, or perhaps even as a result 
of, any formulas that voters use.

Having said all that, I still think Approval voting is a promising idea 
that should be tried -- starting at the local level.

A final note to Mike. Please don't make an a** of yourself again. If it 
makes you feel better, I'll stipulate that you knew all of this already. 
Of course you did. You are the grand master of voting systems (in your 
own mind at least).

--Russ