[EM] 01/05/03 - Two Replies for Olli:

[James Gilmour]

>Donald wrote:   Second reply:
>    Your example of three groups with 33 1/3% each exposes the falacy of the
> Droop quota.  In the event an election method should be faced with
> perfection on the first count, the method should be able to handle
> perfection and report out perfect results.
>
> Hare Preference Voting can handle perfection and will report the results of
> your perfect election as:
>             33 1/3% A,   33 1/3% B,   33 1/3% C
>
> But, Droop Preference Voting cannot handle perfection.  Its math will
> reduce each 33 1/3% down to 25% +1.  The public should not like results of
> 25 A, 25 B, 25 C, and 25% excluded after they have voted a perfect:  33
> 1/3% A,   33 1/3% B,   33 1/3% C.
>
> In a real Droop election the officials most likely will merely declare
> A-B-C as the winners without doing the math of Droop.  In this way they can
> hide the shame of the defective Droop from the public.

These comments seem to be based on a misunderstanding of the purpose of elections,
on a misunderstanding of the purpose of the Droop quota, and on a misunderstanding
of the arithmetic of an STV-PR election using the Droop quota.

I'll (eventually) go back to one of Donald's related comments, but he seems to
think the purpose of an election is to allocate voters perfectly to Hare quota
groups.  That is NOT the purpose of an election.  If it is an election to fill
simultaneously, say, three seats, the purpose of the election is to identify the
three candidates who are most representative of the voters.

If there are three candidates who can each secure a Droop quota of votes (1/4 plus
1, for a three-seat contest), it follows that these are the three winners, because
no other candidate can then secure a Droop quota of votes.  It is not necessary to
continue the transfer of votes until all votes are allocated perfectly to three
Hare quota groups.  In any case, the voters will defeat you, because not all of
them will mark all possible preferences.

If there were a 3-seat election in which three candidates each secured exactly 1/3
of the first preference votes, that is what the STV-PR result sheet would show.
And it would show the Droop quota as 1/4 of total valid vote plus 1.  The
arithmetic is quite clear - three candidates each secured (at least) a Droop quota
of votes at the first stage of the count, so they are the three winners.  There
would be nothing to hide.  There would be no shame.  There would be nothing
defective.

James


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