[EM] Irrelevant Ballots

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[EM] Irrelevant Ballots

Toby Pereira
I've noticed people (mainly Chris Benham I think) talking about "irrelevant ballots", and I just wanted to clear up the definition that people use. My intuitive understanding is that a ballot is irrelevant with respect to candidates A and B if it ranks/rates them equally or doesn't rank/rate them at all. So if A is elected over B then the addition or removal of any such ballots would never cause B to be elected over A.

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Re: [EM] Irrelevant Ballots

C.Benham
Toby,

A while ago some-one coined the "Blank Ballots Criterion" that just said that the result shouldn't change if we add (or remove) some
"blank ballots".

But it struck me that a method that breaches this in spirit would usually meet the letter of it by simply refusing to count such ballots
as "valid".

So I coined "Irrelevant Ballots Independence" that just said that if we add some ballots that do nothing but plump for some candidate
with fewer above-bottom votes than any other candidate and that is ignored or not voted above bottom on all the other ballots then
the result shouldn't change.

It is failed by Bucklin and tends to be failed by methods that use arbitrary percentage thresholds of all the valid ballots as part of their
algorithms.

Chris Benham


On 11/9/2016 8:20 AM, Toby Pereira wrote:
I've noticed people (mainly Chris Benham I think) talking about "irrelevant ballots", and I just wanted to clear up the definition that people use. My intuitive understanding is that a ballot is irrelevant with respect to candidates A and B if it ranks/rates them equally or doesn't rank/rate them at all. So if A is elected over B then the addition or removal of any such ballots would never cause B to be elected over A.


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Re: [EM] Irrelevant Ballots

Toby Pereira
Thank you for the clarification. Would you also consider ballots that rank/rate candidates equally to be irrelevant? For example, if A and B are the clear frontrunners anyway, and a ballot top rates or equal top ranks both candidates and doesn't mention any other candidates, would this be an irrelevant ballot?



From: C.Benham <[hidden email]>
To: [hidden email]
Sent: Wednesday, 9 November 2016, 5:28
Subject: Re: [EM] Irrelevant Ballots

Toby,

A while ago some-one coined the "Blank Ballots Criterion" that just said that the result shouldn't change if we add (or remove) some
"blank ballots".

But it struck me that a method that breaches this in spirit would usually meet the letter of it by simply refusing to count such ballots
as "valid".

So I coined "Irrelevant Ballots Independence" that just said that if we add some ballots that do nothing but plump for some candidate
with fewer above-bottom votes than any other candidate and that is ignored or not voted above bottom on all the other ballots then
the result shouldn't change.

It is failed by Bucklin and tends to be failed by methods that use arbitrary percentage thresholds of all the valid ballots as part of their
algorithms.

Chris Benham


On 11/9/2016 8:20 AM, Toby Pereira wrote:
I've noticed people (mainly Chris Benham I think) talking about "irrelevant ballots", and I just wanted to clear up the definition that people use. My intuitive understanding is that a ballot is irrelevant with respect to candidates A and B if it ranks/rates them equally or doesn't rank/rate them at all. So if A is elected over B then the addition or removal of any such ballots would never cause B to be elected over A.


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Re: [EM] Irrelevant Ballots

Richard Lung

By my system of Binomial STV, all blank ballots and all blank preferences within ballots count. This is justified in its own right, as an expression of indifference that can leave a seat vacant. But it is also necessary to ensure that the exclusion count is not given undue importance compared to the election count.

from
Richard Lung.

On 09/11/2016 15:33, Toby Pereira wrote:
Thank you for the clarification. Would you also consider ballots that rank/rate candidates equally to be irrelevant? For example, if A and B are the clear frontrunners anyway, and a ballot top rates or equal top ranks both candidates and doesn't mention any other candidates, would this be an irrelevant ballot?



From: C.Benham [hidden email]
To: [hidden email]
Sent: Wednesday, 9 November 2016, 5:28
Subject: Re: [EM] Irrelevant Ballots

Toby,

A while ago some-one coined the "Blank Ballots Criterion" that just said that the result shouldn't change if we add (or remove) some
"blank ballots".

But it struck me that a method that breaches this in spirit would usually meet the letter of it by simply refusing to count such ballots
as "valid".

So I coined "Irrelevant Ballots Independence" that just said that if we add some ballots that do nothing but plump for some candidate
with fewer above-bottom votes than any other candidate and that is ignored or not voted above bottom on all the other ballots then
the result shouldn't change.

It is failed by Bucklin and tends to be failed by methods that use arbitrary percentage thresholds of all the valid ballots as part of their
algorithms.

Chris Benham


On 11/9/2016 8:20 AM, Toby Pereira wrote:
I've noticed people (mainly Chris Benham I think) talking about "irrelevant ballots", and I just wanted to clear up the definition that people use. My intuitive understanding is that a ballot is irrelevant with respect to candidates A and B if it ranks/rates them equally or doesn't rank/rate them at all. So if A is elected over B then the addition or removal of any such ballots would never cause B to be elected over A.


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-- 
Richard Lung.
http://www.voting.ukscientists.com
Democracy Science series 3 free e-books in pdf:
https://plus.google.com/106191200795605365085
E-books in epub format:
https://www.smashwords.com/profile/view/democracyscience


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Re: [EM] Irrelevant Ballots

C.Benham
In reply to this post by Toby Pereira
To avoid confusion I usually just use the term "irrelevant ballots" to refer to ballots that in effect don't do anything  except
change the total number of ballots.

To answer your specific question, obviously they should be irrelevant on who should win out of A and B but of course they support
A and B versus the rest so (even though A and B are "the clear frontrunners") they may not be entirely irrelevant.

Chris Benham

On 11/10/2016 2:03 AM, Toby Pereira wrote:
Thank you for the clarification. Would you also consider ballots that rank/rate candidates equally to be irrelevant? For example, if A and B are the clear frontrunners anyway, and a ballot top rates or equal top ranks both candidates and doesn't mention any other candidates, would this be an irrelevant ballot?



From: C.Benham [hidden email]
To: [hidden email]
Sent: Wednesday, 9 November 2016, 5:28
Subject: Re: [EM] Irrelevant Ballots

Toby,

A while ago some-one coined the "Blank Ballots Criterion" that just said that the result shouldn't change if we add (or remove) some
"blank ballots".

But it struck me that a method that breaches this in spirit would usually meet the letter of it by simply refusing to count such ballots
as "valid".

So I coined "Irrelevant Ballots Independence" that just said that if we add some ballots that do nothing but plump for some candidate
with fewer above-bottom votes than any other candidate and that is ignored or not voted above bottom on all the other ballots then
the result shouldn't change.

It is failed by Bucklin and tends to be failed by methods that use arbitrary percentage thresholds of all the valid ballots as part of their
algorithms.

Chris Benham


On 11/9/2016 8:20 AM, Toby Pereira wrote:
I've noticed people (mainly Chris Benham I think) talking about "irrelevant ballots", and I just wanted to clear up the definition that people use. My intuitive understanding is that a ballot is irrelevant with respect to candidates A and B if it ranks/rates them equally or doesn't rank/rate them at all. So if A is elected over B then the addition or removal of any such ballots would never cause B to be elected over A.


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