[EM]CNTT,QLTD ? (enquiry from John Hodges)

Chris Benham cbenhamau at yahoo.com.au
Mon Mar 28 03:00:04 PST 2005


Participants,
I've had a request from John Hodges, who used to
subscribe and contribute to EM.

> could you ask the EM folk for an evaluation of the
properties of CNTT,QLTD? 

That stands for  "Condorcet(Net) Top Tier,
Quota-Limited Trickle-Down", which means "order the
candidates using the QLTD method and then elect the
highest-ordered member of the Smith set".

QLTD is a Bucklin-like method invented by Woodall.
Quoting from one of his papers:

> My first serious attempt to find a rule that would
rival AV resulted in what I call Quota-Limited
Trickle-Down (QLTD). Although this has now been
superseded by DAC, I describe it here because it is
simpler. One starts by crediting every candidate with
all their first-preference votes. If no candidate
exceeds the quota (of half the number of votes cast),
then one gradually adds in the second-preference
votes, then the third-preference votes, and so on,
until some candidate reaches the quota. For example,
it may be that if one credits every candidate with all
their first-preference votes, all their
second-preference votes and 0.53 times their number of
third-preference votes, then exactly one candidate is
brought up to the quota; that candidate is then
declared elected.
>
>
>           

The method fails both Clone-Winner and  Clone-Loser. 
Methods like CNTT,DSC and CNTT,DAC seem to be better
in terms of criterion compliances,but John thinks that
CNTT,QLTD might have compensating practical
advantages.


Chris  Benham

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