[EM] Geographically proportional ballots

[Kristofer Munsterhjelm]

Juho wrote:
> On Aug 29, 2008, at 15:51 , Kristofer Munsterhjelm wrote:
> 
>>>>> One more approach to semi-computerized voting. A computer displays 
>>>>> the personal alternatives and then prints a ballot. This solution 
>>>>> hides the personalized nature of the ballot and still avoids the 
>>>>> problem of voter voting for candidates that he/she should not vote.
>>>>
>>>> One could augment the semi-computerized voting by making it print 
>>>> all candidates
>>> That could be thousands, so maybe a subset in many cases.
>>
>> Just enough to hide the data. One could print out to the nearest 
>> candidate that's, say, a tenth of the population away from the voter.
>>
>> Here I say that a candidate is N voters away from a voter if it's not 
>> possible to make a compact region that includes both the voter and the 
>> candidate, yet has fewer than N voters in it. For simplicity, the 
>> region might be a circle.
> 
> One should maybe avoid the possibility of someone deriving the location 
> of the voter based on the distribution of all the candidates on the 
> ballot. (Also picking fully random candidates may reveal the location 
> since there will be one concentration of nearby candidates.)

This could happen if the voter has a compact region significantly 
different from the rest. For instance, vote-buyers may (theoretically) 
advertise that they're just in range to candidate x, so that x will be 
on his ballot whereas x won't be on all the others in his region.

But if that's not the case, then the only way your deduction will work 
is statistically, and when doing so, it'll be hard to separate a single 
person from the rest of the mass you know is in the close vicinity. If 
you tell A to rank yourself in first place, and you then find out that 
one of the ballots from this area has yourself in first place, you still 
don't know if it's A or not (absent intentional ballot fingerprinting by 
the voter).