[EM] Instant 2-stage plurality/pairwise runoff

Forest Simmons fsimmons at pcc.edu
Mon Mar 18 16:24:50 PST 2002

On Sun, 17 Mar 2002, Bart Ingles wrote:

> atarr at purdue.edu wrote:
> >
> > As an interesting side note, the nation of Sri Lanka (just south of India)
> > recently switched over to such an instant two stage runoff (we called it ITTR in
> > a thread a few months ago, for instant top two runoff).  Thus far, their ITTR
> > elections have produced the same results that a plurality election would have.
> > It should be interesting to watch.  ITTR is better than IRV, although both are
> > pretty bad.
> ITTR sounds the same as the "Supplemental Vote" now used in London.  I
> don't know whether it's better than IRV, but I would say it's
> considerably worse than traditional Two-Round Runoff.  The reason is
> that with ITTR, you need to be able to anticipate which second-choice
> candidates will survive to the final round, otherwise your second choice
> could be eliminated at the same time as your first choice.  With
> traditional runoff, you get to see who's in the runoff before voting in
> the runoff.

What we were calling ITTR used preference ballots with all of the
candidates ranked, so that Two-Round Runoff could be faithfully simulated.

I don't know if the Sri Lanka system is ITTR or Supplemental vote; it's
not clear from the description.


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