From: Jameson Quinn [mailto:[email protected]] Sent: Monday, June 17, 2013 3:14 PM Subject: Re: Participation Criteria and Bucklin - perhaps they *can* work together after all?
Unfortunately, Bucklin systems fail that one too. Hold on a sec. Let me think this through. If we are using a Bucklin system, perhaps a strictly ranked one, and X is currently winning. Adding a single ballot that has X ranked as the highest does two things: it changes the threshold, and it awards one more vote to X. The only way it can hurt X - ie, cause X not to win, is if the harm in changing the threshold is greater than the benefit of getting another first place vote. That's the key to why Buckley keep failing Participation!! I think I finally grasped the essential Participation flaw with Buckley!! Each added ballot changes the threshold. Changing the threshold will either have NO effect, or it will change how "deep" we have to go to find a winner. In this case, even if we know ALL the ballot we are adding have X at the top, adding even a single on if it changes the threshold enough will suddenly bring into your totals all the next place rankings for the existing ballots. In other words, Buckley fails Participation because it is not a "smooth" curve, it is a fragile one that can leap and lurch, if you see what I am saying. In its own way, Buckley is as unpredictable as IRV. Both have fractal moments where a very small change can completely swamp the system and produce a very different result. Any system as - what's the right word, jagged? sensitive? fragile? is going to have one or more issues with appealing to our common sense, because each has a point in which a tiny change can cause a system wide shift. Am I right? I don't know what this kind of trait is called, this oversensitivity, this ability to suddenly shift from condition One to Condition Two with no smooth transition points in between - but I think these kinds of systems will suffer from problems like these. Now, for all I know ALL voting systems have this kind of issue - we'll see. -Benn Grant eFix Computer Consulting <mailto:[email protected]> [email protected] 603.283.6601
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