A great deal of interesting work and research has gone into the study of voting procedures over the years. There are many different ways to vote and to tally those votes. I will try to summarize the high points of several of these voting methods in this and subsequent posts. Remember that all these boil down to the same thing for simple, single-choice votes, so the differences between algorithms only matter for multi-choice elections.
Instant Runoff Voting (IRV) and its variants, including Single Transferable Vote (STV), require a voter to rank the multiple candidates in preference order. The Ethosphere GUI can facilitate that kind of voting using a simple drag-and-drop interface, allowing a member to arrange all the candidates in the desired order, favorite on top. It is not necessary that each member rank all candidates, allowing for the possibility that new alternate props can be added after the member has already voted.
Calculating the winner of an IRV election is somewhat complicated and, if done by hand, time consuming. In Ethosphere of course, it will be done by computers so this isn't much of an issue (but see the transparency discussion in Pros and Cons below). Basically, it works like this. First, the first place votes are tallied for each candidate. If one of the candidates has enough first place votes to exceed a defined threshold, say 51% simple majority, that candidate is declared the winner in the first round and the election is over. However, if no candidate receives a majority of votes, no clear winner can be declared and the race goes to a runoff election. Rather than going to the trouble and expense of conducting a second election, we use the ranking information on the original ballot to break the tie (hence the name, instant runoff). First, the candidate who had the lowest number of first place votes is eliminated, and the ballots of all members who voted for it are re-examined. For just those ballots, we take the second place choices and add them to the first place totals of the remaining candidates. This process is repeated until one of the candidates has the required majority.
Pros and Cons
IRV has a reasonable track record of use in practical, political elections throughout the world. Australia and Ireland have both used this method for many years. Many U.S. states and local governments use IRV for local or specialized elections. The Academy Awards for motion pictures also uses it. (Coincidentally, the Oscars are being broadcast tonight.) The practical, real world results from these various experiments have been mixed. It is undoubtedly better than plurality voting, but it's still vulnerable to strategic voting, of course. Duverger's Law, which says that plurality voting systems will always, eventually result in a two-party division of candidates, does not seem to apply to IRV, although in several real world cases it has resulted in just two viable political parties emerging.
Of the dozen or so standard criteria by which experts typically judge voting systems, IRV fails a couple of them, sometimes leading to unexpected, and unwanted behaviors. For example, IRV is not "consistent," meaning that if the membership is divided into two parts and votes counted separately, even if the same candidate wins in both sub-elections it may not be the winner when the votes are combined together. A different but related drawback is that IRV is not "summable," meaning it is not tractable to count votes in a sub-group, say a precinct, and pass the totals up to be combined at a central election office or some higher tier.
Like plurality voting, IRV tends to favor the more extreme candidates over the more moderate ones. Suppose there is an IRV election where candidate A has 51% and candidate C has 49% of the first place votes, but candidate B, the moderate candidate, has 80% of the second place votes. In other words, most of those members who favor candidate A and most of those who favor candidate B would all be okay with candidate B if it came to that. IRV would still declare A as the winner in the first round. In this admittedly contrived example, nearly half the members would be very unhappy with the result, having lost to their least favorite candidate by only a small margin. In Ethosphere, more so than real life, it is easy for unhappy members of a teamspace to secede and form their own teamspace. Of course, this tendency is undesirable and counter to one of the important goals of the system.
An equally serious practical drawback for this method is its subjective impact on transparency of an election. Explaining why a particular candidate prop won an election is somewhat difficult if there were two or three, or more, rounds of instant runoff required. Imagine explaining that candidate A won because, "More members ranked candidate A as their third choice and candidates X or Y as first or second, and candidates X and Y received the fewest first and second place votes."