[EM] Election-Methods Digest, Vol 62, Issue 10

[Kristofer Munsterhjelm]

James Gilmour wrote:

> It is extremely important to refer to STV as the SINGLE Transferable
> Vote, because each voter must have only one vote to ensure PR. This
> distinguishes STV from all multiple vote systems, like
> Multi-Member-FPTP or the Cumulative Vote.  It is also important to 
> emphasise the Single TRANSFERABLE Vote, because PR cannot be obtained
> (except by chance) if that single vote is not transferable (as in the
> Single Non-Transferable Vote).

That's not completely true. Some methods that don't use transferable 
votes have a strategy equilibrium where there's PR. Consider, for 
instance, SNTV (you get one vote, the n best wins), under party control. 
  If a given party fields too many candidates, their votes are spread 
too thin and they lose. If the party fields too few candidates, they 
miss some seats they could otherwise have acquired. Thus each party 
fields a number of candidates proportional to that party's support, and 
instructs the people to vote randomly for one of the party's candidates 
(so as to spread the votes evenly).

You may argue that the random part of the allocation constitutes chance, 
but it doesn't have to. When Taiwan was using the SNTV, one of the 
parties instructed the voters to decide which candidate to vote for 
according to the voter's birthday. That's uniform but it's not random 
(since the birthday remains the same).