[EM] Let's fill the vacancy by Bjarke's words:

[Donald Davison]

Greetings List Members,

Bjarke wrote: "I think the best method, if the replacement must be
determined from the original STV election result, is to eliminate the
leaving candidate from all ballots, then repeat the STV count with the
constraint that the n-1
remaining seats must be kept (cannot be eliminated)."


Donald here:  I agree with these words of Bjarke, this is the best method.

Having said that, I would also like to say that when the replacement is
determined (by Bjarke words), we will find that he is the same person as
the first runner-up in the original election, it's in the math.

Donald,

 * * * *

Jim Riley wrote:
"2. Recount the ballots eliminating the preference for the vacant
member (treating him as having withdrawn before the election), but
adding a constraint that the originally elected members could not be
excluded.

Advantages: To a slightly less extent than (1), the collective set of
members should be fairly representative of the constituents views.
Votes that had elected the now vacant member, will tend to be
distributed to like-minded candidates.  And unlike (1), no sitting
members could be displaced.

Disadvantages: A possibility that some candidates could end up with
more votes than one of the previously elected, non-excludable
candidates, and still not be elected.  Though not necessarily unfair,
it could have the appearance of being so, delegitimizing STV."
[end of Jim's quote]


Donald here:  While it is true that it is possible for a losing candidate
to receive in the recount a few votes more than one of the sitting members,
if the public is well informed that the sitting members are to be retained
because they did win in the original election and this current count is not
a recall effort, then the public should accept the results.

By the way Jim, thank you for the fine study on this vacancy subject that
you presented.  I forwarded it on to two other lists.

Donald,


* * * * *

Deane Crabb wrote: "The PR Society of Australia argues strongly for a
recount, but there is some difference of opinion on which recount method is
used.  I tend to favour just recounting the quota of votes that elected the
vacating member as it is these votes that initially counted towards
electing someone and therefore
these should choose the replacement."

Deane Crabb
Secretary
PR Society of Australia


Hi Deane,
Donald here, just recounting the quota of votes that elected the vacating
member would only be valid if all these votes had the same next preference,
but that will never be the case.  The next preferences of these voters will
be so divided that no candidate will even come close to having an original
quota.  You will end up electing the replacement by a minority of a quota.
The result will not be proportional to the sitting members.  We must use
all the ballots in the count in order to again get a proportional body of
members.

Proportionality can only be gained via the STV math that includes all the
candidates and all the ballots.

Donald,