Approval Voting vs. IRV
Here are several reasons why we at The Center for Election Science believe that Approval Voting is a much more democratic election method than Instant Runoff Voting. Throughout this page, we will cite several analysis pages from ScoreVoting.net, whose primary author is a Princeton math Ph.D. named Warren Smith, who has been studying election issues for well over a decade.
Computer simulation studies show that Approval Voting is superior to IRV as measured by “Bayesian regret“, an objective “economic” measure of average voter satisfaction. The following graph, taken from page 239 of William Poundstone’s book Gaming the Vote displays Bayesian Regret values for several different voting methods, as a function of the amount of tactical voting.
Approval Voting can be done with the same ballots voters are used to. You just remove the rule that says “vote for only one”. Instant Runoff Voting requires a different ballot.
As a result, IRV results in about seven times as many spoiled ballots as Plurality Voting, on average. Whereas Approval Voting experimentally results in about one fifth as many spoiled ballots.
Another result is that Approval Voting can be handled by any kind of voting machine capable of handling multiple Plurality elections, i.e. every voting machine in the USA, without modification. IRV requires upgrades to either hardware, or at the very least, software. And its complexity has been shown to incentivize the adoption of fraud-prone electronic voting machines.
As FairVote executive director, and prominent IRV advocate, Rob Richie admitted in print in 2008, no voting machine in the USA comes, out of the box, ready to handle IRV elections. Many computerized voting machines have been decertified by their states, in, e.g. California, Colorado, Ohio. See this page for a much deeper dive into this issue.
IRV cannot be ”counted in precincts” – only centralized counting is possible – necessitating a big change to procedures and a security hit because a small central conspiracy then can throw elections (whereas fraud at a precinct level is inherently limited in scope, and in the aggregate will partially cancel out due to the fact that the administrators of different precincts will be of different parties).
This can also cause delays in getting final results. For instance, this message appeared on the San Francisco city government website for several weeks after their 2008 RCV elections.
“Due to the requirement that all ballots must be centrally tallied in City Hall and not at the polling places, the Department of Elections has not set a date for releasing any preliminary results using the ranked-choice voting method.”
Approval Voting completely eliminates the “spoiler” problem, whereas IRV merely mitigates it. Here’s a video explanation by CES co-founder Andrew Jennings, who got his math PhD with a focus on the mathematics of voting.
IRV is most likely to lead to tie and near-tie chad-counting lawsuit nightmare scenarios. Score Voting (aka “Range Voting”) is least likely. Approval Voting is the simplest form of Score Voting. (Mathematically, voting for a candidate is like giving that candidate a score of “1″, whereas not voting for a candidate is like giving the candidate a score of zero.)
IRV exhibits a tremendous number of crazy pathologies. All voting methods can exhibit certain problems, but the problem is particularly severe for IRV. Here is a simple example of an IRV election which simultaneously exhibits numerous pathologies. Here is another ”worst case scenario” example, which is much less probable, but shows how severely IRV can potentially fail.
IRV is extremely susceptible to tactical exaggeration, which causes it to degenerate approximately into ordinary Plurality Voting. (IRV proponents often make this very criticism of Approval Voting, but they are mistaken.)
Approval Voting is better. In addition to the superior Bayesian Regret performance as seen in the above graph, there are two theorems about the relatively mild (some would say good) behavior of Approval Voting in the face of tactical behavior.
- Approval Voting will, under plausible voter tactics, elect a Condorcet (“beats-all”) winner whenever one exists.
- Approval Voting will maximize the number of “pleasantly surprised” voters.
IRV has maintained massive two-party domination everywhere it has seen long-term widespread use. The most noteworthy example is Australia, where IRV has been used in their House of Representatives since 1918.
This seems to be a result of the fact that voters insincerely exaggerate their rankings. For instance, an IRV voter who favors a minor party will tend to insincerely rank his favorite major party candidate in first place. Why? Because…
- That actually is the best strategy with IRV.
- Most voters don’t understand the mathematics of their voting system, so when faced with a ranked ballot, they will tend to use what we call the “naive exaggeration strategy“. It doesn’t even matter whether it’s the best move from a statistical point of view. They’ll just do it. (I will add a link soon to a future page which shows irrefutable evidence of this.)
Matt Gonzalez, Ralph Nader’s former running mate, was generous enough to allow us to publish this essay on his personal blog. It gives a detailed account of why Score Voting and Approval Voting are so much more fair to minor parties, as well as reiterating our point that IRV is harmful to minor parties.
Accurate representation for minor party and independent candidates
On Election Day, Tuesday November 6, 2012, the Political and Electoral Reform of the Occupy Wall Street conducted an alternative voting experiment at polling places in Manhattan’s 69th State Assembly District. The group was granted credentials from the NYC Board of Elections to conduct the exit-poll style experiment inside the city’s official polling places. The experiment compared Plurality Voting (traditional “vote for one” method) with Approval Voting, Score Voting and Instant Runoff Voting. Below are graphs revealing the totals for these four systems.
Let’s first look at the Plurality Voting results, to establish a baseline.
While this district was clearly not representative of the overall American electorate, note the relative strength of the minor party candidates compared to the major party candidates. For instance, Green Party candidate Jill Stein received one vote for about every 27 votes for Obama. (The study authors note that their results were consistent with the official election results.)
Now compare to Approval Voting.
The Green Party now receives 58% as much support as the Democratic Party. This is over a 15x improvement in the Green Party’s strength relative to the Democratic Party, compared to where they were with Plurality Voting. The other minor party and write-in candidates also fared dramatically better.
Now let’s look at Instant Runoff Voting.
Because Obama won in the first round of voting, we don’t see the depth of support for the minor party candidates. These results actually look almost identical to the Plurality Voting results! And even when IRV elections require several rounds of elimination, the news headlines rarely shed light on the details. And how would they do so if they wanted to? There is no good way to summarize the results of an IRV election into a simple figure that says, “here’s how many votes each candidate got.” This gives the false impression that the minor party candidates had far less support than they really did.
Finally, for completeness, we show the Score Voting results. Voters could score each candidate on a scale from zero to five. The results represent the percentage of total possible points gotten by each candidate. (Note that Approval Voting is effectively just Score Voting on a zero to one scale.)