[maemo-community] STV voting strategy

From: Dave Neary dneary at maemo.org
Date: Fri Mar 20 12:00:58 EET 2009

Frantisek Dufka wrote:
> The biggest difference between ranking and STV is that with STV you
> really have only _single_ vote (the S in STV) and only your first choice
> counts if your candidate is not eliminated further in the process.

Not quite accurate - there is also the T (transferable) in STV, which
applies to surplus votes. We can see this effect in rounds 2 and 3, the
transfers from GA and Jaffa elected Tim Samoff, for example.

Jaffa's surplus of 21 transferred: Tim +8, Andrea +1, anidel +1, Jamie
+2, Kees +3, sjgadsby +3, qole +3

GA's surplus of 14 transferred: Andrea +1, Jamie +2, anidel +1, Kees +3,
sjgadsby +3, qole +3 (Tim was elected at that stage)

So over 40% of the votes for Jaffa, and a third of the votes for GA got
transferred, in proportion to the number of #2 votes for each of those

Since Tim, Kees, sjgadsby and qole were the most popular transferees
from the surplus, this allowed then to build a cushion in later counts
and they were protected from elimination in later rounds.

One can imagine a situation where one incredibly polarising candidate
gets a lot of first preferences (say 20) but does not receive any of
those transfers from surpluses or eliminations - he won't get elected.

So I disagree - strategically voting for another candidate than your
favourite as #1 is not necessary to make your vote count. Your second
preference will get taken into account if your favourite candidate has a
surplus, or is eliminated.


maemo.org docsmaster
Email: dneary at maemo.org
Jabber: bolsh at jabber.org

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