Propagation:

The Democratic Piece grafted Fractional thresholds in STV

5 ideas sprouting

1. Well, yes, but its population is only 62,000 or so…

   Seed planted by Tom Round — 10 December 2007 @ 23:36

2. I became president of my high school student council by 2 votes. The system was FPP, and there were at least 4 viable candidates.

   Apparently the Duverger rule does not operate among 15-17 year-olds. Yet more evidence that response to institutional incentives requires repeat interaction with like institutions - and maybe even some socialization.

   Seed planted by Jack — 11 December 2007 @ 01:41

3. Duverger’s Law won’t operate where voters are very strongly loyal to their own tribe’s first-choice candidate and utterly indifferent to all others, and are willing to risk losing completely rather than to vote insincerely. Exhibit A: Papua New Guinea. Exhibit B: high school…

   By the way, the Proportional Representation Society of Australia’s “PR Manual” caters for very small electorates by providing for the votes to be counted (and the quota to be calculated) to four decimal places. Otherwise too many “vote points” get lost via surpluses. So, if 80 members of the “Utopia Tennis Club” are electing 5 executive committee members, the quota will be 13.334 votes rather than 14 votes, thus leaving the runner-up with 13.330 votes, rather than 10, and reducing the risk of a tie.

   Seed planted by Tom Round — 11 December 2007 @ 03:41

4. Fractional thresholds in STV

   Ties can be a big problem in STV elections with small electorates. They can make people question the legitimacy of the system in general and an election in particular.

   Scion grafted by The Democratic Piece — 11 December 2007 @ 18:05

5. Well, ties can be a problem in any voting system, full stop (F, l, o, r, i…, anyone?).

   Having said that, I concede that both the risk and the seriousness of ties is probably exacerbated when the system is based on elimination of the lowest-polling players, because:

   (a) the order of elimination early on, among the “minnows”, can visibly affect which of the “whales” wins the final showdown (a criticism that Condorcet, Approval, Borda etc advocates often make against STV/ IROV); and

   (b) a tie is statistically more likely to arise between two minor parties with, say, 1,000 votes each than between the Big Two parties with 100,000 votes each (the latter being the only type of tie that matters under first-past-the-post systems).

   Which means STV/ IROV opponents can point to the spreadsheet and say in hindsight, quite correctly, “One extra vote (or a lucky coin toss) for Screaming Lord Sutch against Ralph Nader could have changed the whole result.” For want of a nail, the kingdom could have been lost.

   For this reason, I don’t favour breaking ties either by drawing lots or by status quo (ie, favouring whichever candidate was ahead when the tied contenders were last unequal).

   Rather, I propose that, if N (2 or more) candidates are tied and one has to be eliminated first (ie, you can’t just bulk-eliminate them all), we should:

   (a) re-examine all the ballots for their N preferences among the Tied Ones only;

   (b) give each Tied One one demerit for each ballot on which s/he is ranked lowest of those tied; and

   (c) exclude whichever of the Tied Ones gets the most demerits.

   Ie, if 2 are tied, this means a straight pairwise count.

   If, say, 3 are tied, this means Approval Voting among those three.

   This does mean some more work, but a more robust result; and

   (i) with a small electorate, higher likelihood of a tie arising, but less work to re-examine all ballots if one does; and

   (ii) with a large electorate, smaller likelihood of a tie arising, albeit more work re-examining all ballots if one does.

   Seed planted by Tom Round — 12 December 2007 @ 06:38

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