[EM] STV with which quota?

[stephane.rouillon at sympatico.ca]

Yes James I red it yesterday.

But all it proves is that sometimes it can happen
that Droop quota leads to a more proportional result than Hare quota.

Although I haven't yet finished my analysis, my actual feeling
is that Hare would usually lead to a more proportional result.
This is the point I would like to benefit from any EM member
analysis or I'll do it myself.  All I have concluded yet is that using any quota, any candidate that reaches the Droop quota will get elected.

Actually I presented STV yesterday in a meeting and insisted on the number of seat per district to maximize proportionality instead of
chosing any quota. 

Sincerely yours, Stéph.

> De: "James Gilmour" <jgilmour at globalnet.co.uk>
> Date: 2005/10/11 mar. PM 08:08:10 GMT-04:00
> À: <stephane.rouillon at sympatico.ca>, 
> 	<election-methods at electorama.com>
> Objet: RE: [EM] STV with which quota?
> 
> Stephane.rouillon Sent: Tuesday, October 11, 2005 2:45 PM
> > 
> > I learned STV about three years ago.
> 
> I learned about STV more than 43 years ago, but I am still learning.
> 
> > At the time Hare quota appeared to me the most
> > proportional quota and thus, in my humble opinion,
> > the best quota.
> > 
> > Now why is Droop better?
> > Any comment?
> 
> Consider the following example:
> In an STV-PR election with 120 voters for five places, the HARE quota would be 24 votes (= 120 / 5).
> Suppose the election is contested by two parties (R and S) with three candidates each (A, B, C).
> With first preference votes as shown, RA and RB would be elected at the first stage.
> 
> Stage 1
> RA 24 elected   SA 19
> RB 24 elected   SB 19
> RC 16              SC 18
>       64                   56
> 
> Of the four continuing candidates, candidate RC has the fewest votes and so is excluded.  No matter what preferences are
> marked on those papers, SA, SB and SC will then be elected.
> 
> Stage 2
> RA 24 elected   SA 19 elected
> RB 24 elected   SB 19 elected
> RC 16 excluded  SC 18 elected
>       64                     56
> 
> Applying the Hare quota, supporters of the larger opinion group (party), who constitute an absolute majority, elect only
> two candidates, while the smaller group elects three.
> 
> 
> For this election, the DROOP quota would be 20 = (120 / (5 + 1)).  With first preference votes as before, RA and RB
> would be elected at the first stage, each with a surplus of 4 votes above the quota. 
> 
> Stage 1
> RA 24 elected   SA 19
> RB 24 elected   SB 19
> RC 16              SC 18
>       64                   56
> 
> If we (reasonably) assume that these surplus votes transfer to the remaining candidate of party R, candidate RC will be
> elected, and SA and SB will take the two remaining places.
> 
> Stage 2
> RA 20 elected   SA 19 elected
> RB 20 elected   SB 19 elected
> RC 24 elected   SC 18
>       64                    56
> 
> The outcome with the Droop quota is that the supporters of  the larger group elect three candidates and the smaller
> group elects two.
> 
> QED.
> James Gilmour
>