[EM] Strategy and Bayesian Regret

[Jameson Quinn]

2011/11/1 Kevin Venzke <stepjak at yahoo.fr>

> Hi Jameson,
>
>
> --- En date de : *Ven 28.10.11, Jameson Quinn <jameson.quinn at gmail.com>*a écrit :
>
>
> De: Jameson Quinn <jameson.quinn at gmail.com>
> Objet: Re: [EM] Strategy and Bayesian Regret
> À: "Kevin Venzke" <stepjak at yahoo.fr>
> Cc: election-methods at electorama.com
> Date: Vendredi 28 octobre 2011, 11h44
>
>
>
>
> 2011/10/28 Kevin Venzke <stepjak at yahoo.fr<http://fr.mc296.mail.yahoo.com/mc/compose?to=stepjak@yahoo.fr>
> >
>
>   Hi Jameson,
>
> I am a little short on time, to read this as carefully as I would like,
> but if you have a
> moment to answer in the meantime:
>
> --- En date de : *Ven 28.10.11, Jameson Quinn <jameson.quinn at gmail.com<http://fr.mc296.mail.yahoo.com/mc/compose?to=jameson.quinn@gmail.com>
> >* a écrit :
>
> voting is best. But how do you deal with strategy? Figuring out what
> strategies are sensible is the relatively easy part; whether it's
> first-order rational strategies (as James Green-Armytage has worked out<http://www.econ.ucsb.edu/~armytage/svn2010.pdf>)
> or n-order strategies under uncertainty (as Kevin Venzke does)
>
> 3. Try to use some rational or cognitive model of voters to figure out how
> much strategy real people will use under each method. This is hard work and
> involves a lot of assumptions, but it's probably the best we can do today.
>
>  As you might have guessed, I'm arguing here for method 3. Kevin Venzke
> has done work in this direction, but his assumptions --- that voters will
> look for first-order strategies in an environment of highly volatile
> polling data --- while very useful for making a computable model, are still
> obviously unrealistic.
>
> [end quotes]
>
> I am very curious if you could elaborate on my assumption that voters will
> "look for
> first-order strategies in an environment of highly volatile polling data."
> I'm not totally
> sure what you mean by first-order vs. n-order strategies,
>
>
> First-order strategies are strategies which work assuming all other
> factions' votes are unchanged. Second-order strategies either respond to,
> or defend against, first-order strategies. I guess that your system,
> through iterated polling, deals with "respond to", but it is incapable of
> "defend against".
>
>
> Hm, I'm really unsure what the latter distinction is.
>
> It's true that my voters seem unwilling to risk ruining the result as a
> form of threat
> or deterrent to other voters. I suppose this is because my voters don't
> understand
> how other voters might hypothetically choose to operate. But I'm not sure
> if this
> is what you're talking about.
>
>

More or less. Consider the following game matrix for groups A and B, with
the upper left being the "current" poll, and payoffs in the form (A,B):

Strategy for A:    x    y
Strategy for B:
p                (5,5) (5,5)
q                (3,9) (0,0)

Strategy y is a defensive strategy for group A. Your voters will never see
it, and even if they did, it would always backfire for them unless they saw
it one step ahead, because group B would not anticipate it.


>
>
>
>   and whether your criticism
> of unrealism is based on "voters will look for..." part or on the "highly
> volatile polling
> data" part.
>
>
> Some of the former (lack of defense), but mostly the latter.
>
> Also, it's not so much a criticism, as a pointer for what comes next. You
> have *absolutely* gone farther than anyone else I know of in exploring
> the motivators and consequences of strategy across voting systems, and if
> my appreciation of that fact didn't come through, I'm sorry.
> (Green-Armytage has some answers you don't about motivators, and Smith's
> IEVS has some about consequences, but your work is by far the best for
> combining the two.)
>
>
> No need to apologize for anything. I'm open to criticism at least if I can
> understand
> it. Personally, aside from the above mentioned point, my major criticism
> of my sims
> is that it can't consider nomination strategy. There is no way to show
> whether a
> given set of candidates is a realistic set of nominees for the electorate
> under that
> method.
>
> I don't really understand what you might mean about the motivators and
> consequences. Maybe you say in later posts I haven't read yet.
>

I mean that you consider strategy in terms of its consequences for the
strategic group (motivators) and its consequences for the electorate as a
whole (consequences). Green-Armytage and others have done the former, Smith
has done the latter, but you've done best at doing both together (to my
knowledge).


>
>
>
>
>
>   I wonder if this volatility is a matter of degree or a general question
> of
> approach.
>
>
> Well, I've never seen you try to justify the volatility in terms of
> realism. It's a computational trick, to prevent excessive equilibrium, from
> what I can tell. That is, your unrealistic (perfectly rational in some ways
> but utterly lacking in any meta-rationality) voters may need this
> unrealistic assumption to give more-realistic answers, and if so, then
> "fixing" this one issue is not the answer. (If there were no volatility, I
> think that your system would end up comparing a lot of 100%/0% numbers,
> which doesn't discriminate very well between systems.)
>
>
> Well, what would be a realisic way to simulate the uncertainty of polling
> in real
> life? A given poll in reality usually only consults a tiny percentage of
> the electorate.
> Thus you get "statistical ties." So I think it's fairly accurate to
> simulate this by
> having random percentages of the voting blocs participate in each poll.
>

But, unless I'm mistaken, the volatility of your polls is much higher than
realistic statistical error for typical polling samples of hundreds of
voters. And furthermore, I speculate if you did use realistic statistical
error, you would find unrealistically dichotomous strategic percentages,
which would in some cases make it hard to distinguish the quality between
two methods (because 0=0 and 100=100). If my latter speculation is true,
the high volatility can be seen as a trick you've consciously chosen to
use; the unrealistic polls compensate for the unrealistic voters and give
more-realistic overall results.

Jameson


>
> Kevin
>
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>
>
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