[EM] Election-Methods Digest, Vol 106, Issue 2

[Kristofer Munsterhjelm]

On 04/05/2013 01:50 AM, Forest Simmons wrote:
> Kris,
>
> Optimal MJ strategy is still approval strategy.  You can instruct the
> voters to make absolute choices, but you cannot enforce it.  Their
> willingness to abide by the instructions is purely psychological.  The
> same psychology will work, only better for Consensus Threshold Approval.

True, but B&L have some evidence that

- the grade ballot in conjunction with MJ produces that kind of 
psychological willingness,
- an Approval ballot as usually phrased induces relative comparisons 
instead,
- and the text (instructions) on a ballot can reduce or increase the 
degree to which the voters make relative choices.

They also suggest that the grade format itself is important in creating 
a setting where the voters have a psychological willingness to make 
absolute choices. They use two arguments:

First, that grades have common meaning as categories in themselves 
whereas a finely graduated scale induces a numerical (comparative) kind 
of thinking;

and second, that MJ, not caring about the distances between the grades, 
supports a view where grades are seen as categories in themselves, and 
thus where it's natural to do absolute comparisons rather than relative 
ones.

What I mean by "not caring about the distances between the grades" may 
need a little more explanation. Say the voters have a common concept of 
the grades as being points from -10 to 10 on some utility scale. Then 
say there's an MJ election and X wins. After the election, perturb the 
grades-utility mapping according to some monotone transformation and run 
the MJ election with the same underlying utilities again. X will still win.

Unless I'm mistaken, I think that'll be true of any system that only 
considers the order of the ratings (as median does, picking the 
middlemost) rather than making use of the ratings' numerical value. And 
since it only makes use of the order of the ratings (the grades, in this 
case), it doesn't need to assign an explicit value to any of them. 
They're just letters and it only needs to know that an A is better than 
a B and so on down.

Is that true of CTA as well?