On Tue, Mar 24, 2009 at 2:30 AM, Dave Ketchum <[email protected]> wrote: > Let's try it slowly for IRV, assuming multiple districts to avoid shortcut > temptations: > > 1 Count ala Plurality. If leader has a majority, that is winner. > > 2 Sum vote counts, starting with weakest count and ending before doing the > next candidate that would make a majority. None of those counted could win, > so mark them all as losers and go back to step 1.
That isn't true. The rule is actually that you can eliminate the weakest N candidates in one step, if the sum of their votes is less than the (N+1)th weakest candidates. The procedure is then to find the largest possible N. 40: A 25: B 15: C>E>B 9: D>E>B 7: E>B 4: F>E>B Round 1: A: 40 B: 25 C: 15 D: 9 E: 7 F: 4 According to your rules, eliminate F+E+D+C. Eliminating B as well would cause a majority of votes, so B is safe. Round 2: A: 40 B: 60 B wins However, with full IRV, the results are eliminat F Round 2 A: 40 B: 25 C: 15 D: 9 E: 7+4 = 11 F: - Eliminate D Round 3 A: 40 B: 25 C: 15 D: - E: 9+11 = 20 F: - Eliminate C Round 3 A: 40 B: 25 C: - D: - E: 20+15 = 35 F: - Eliminate B Round 4 A: 40 B: - C: - D: - E: 35+25 = 60 F: - E wins So, the result is different. >> Less formally, the method is summable if you can "count in precincts" to >> produce managable data chunks that can then be combined to get the result >> for all precincts or districts involved, no matter the size of each >> district. >> > Not clear how this helps. You have to get the totals for round 1 to decide > how to proceed - matters not how many chunks. I guess IRV is "summable in precincts, subject to central office instructions". An election can be verified by checking all the precinct sums/counts and that the central instructions were correct, assuming that the precinct sums were also correct. ---- Election-Methods mailing list - see http://electorama.com/em for list info
