[EM] Question about a news report and nomenclature

[James Gilmour]

 Paul Kislanko asked (order reversed):
> 
> If that is what IRV is, what is the difference between IRV and STV?
> 
IRV is STV applied to a single-seat election.  If no candidate has as many or more first preferences
than all the other candidates combined, the candidate with fewest votes is excluded and those votes
are transferred to the second preferences marked on the ballot papers.  And so on until some one
candidate has as many or more votes than all continuing candidates.

> In any case, they called it "Instant Run-off" but when they 
> described the method it sounded to me to be what this list 
> would call Single Transferable Vote - (the ballots whose 1st 
> place candidate receives the fewest first place votes in the 
> first counting are treated as if the second place candidate 
> was ranked first in the second round, and so on).

This is an unusual way of describing STV vote transfers, but I suspect it gives the same answer in a
single-seat election.  "STV" is more commonly used as "STV-PR", ie in multi-seat elections.  Then
election is by quota and you need to transfer surplus votes above the quota from candidates who are
elected as well transfer votes on exclusion of candidates who do not have enough support to be
elected.

James Gilmour