Score Then Automatic Runoff (STAR) voting is a single-winner voting method that allows voters to rate candidates on a scale from 0-5 like they would a rate a book or a movie. The two highest scoring candidates advance to an automatic runoff in which the candidate preferred by the majority of voters wins.
How Does STAR Voting Work?
Here's a quick overview of the STAR voting method:
Here's a deeper dive into STAR voting's motivation and history:
STAR Voting Highlights
STAR Voting History
STAR Voting was created in 2014 after a group of election scientists from around the nation gathered at the Equal Vote Conference at the University of Oregon. Necessity is the mother of invention and STAR Voting emerged as a new model for fair elections. A hybrid of Score and Instant Runoff Voting, STAR combines the best aspects of both to offer more accurate results than either. Learn more here.
While single-winner STAR is an excellent way to vote for positions such as mayor, governor, or president, in most democracies around the world, deciding who will fill legislative seats is typically done using a multi-winner voting system. There are two main types of multi-winner STAR: Bloc STAR and Proportional STAR.
Bloc STAR is run essentially as multiple iterations of single-winner STAR. The first winner is chosen using single-winner STAR, and then the exact process starts over again with the same ballots to find the next winner, except that the candidate who already won is removed from consideration. This method can work well at electing high-utility candidates in non-partisan races without clear ideological lines. Unfortunately, when the partisan make-up becomes more polarized, this system virtually guarantees that the majority party will win all available seats.
For example, imagine a legislative district with 5 seats up for grabs and the partisan make-up of the district is 60% from party alpha and 40% from party beta. For simplicity, let's say all alpha voters score all alpha candidates higher than any beta candidates, and all beta voters score their candidates higher in the same way. In the first round of bloc STAR, an alpha candidate is elected since the alpha party has a clear majority. However, since the exact same ballots are used for the second round, and all alpha voters scored alpha candidates higher than beta candidates, the second seat is also given to an alpha candidate. This process continues, ultimately giving all 5 seats to alpha candidates.
Proportional STAR is one of various multi-winner voting methods that falls in the category of Proportional Representation (PR) voting systems. Proportional Representation means that the percentage of legislative seats won by a party roughly matches the overall percentage of the vote earned by that party, even if that percentage is fairly low.
Multi-winner Proportional STAR begins the same as single-winner and bloc STAR with voters scoring candidates 0-5, and the two candidates with highest scores advancing to a runoff in which the one who most voters prefer wins. Here is where the systems diverge. Instead of using the same ballots for subsequent runoff rounds, Proportional STAR treats the winning candidate's highest scoring voters as "represented", and removes their ballots from the score tallies for future rounds. The number of highest scoring ballots to remove is determined by a quantity known as the Hare quota, which is the number of total voters (T) divided by the number of open seats (S), or T/S. If we use vote percentages, T equals 100, so a 4-winner district would have a Hare quota of 100%/4=25%. Using this example quota, the 25% of ballots who scored the first winning candidate the highest are removed from consideration. The total scores of each remaining candidate are recalculated, and the next automatic runoff round proceeds. This process continues until all seats have been filled.
Using the same example as we did with bloc STAR, the winning quota is calculated as 100/(5)=20%. Let's say one of the alpha candidates receives the highest overall score and wins the automatic runoff round. The ballots which scored that candidate the highest are then removed from score totals. Since a large chunk of alpha voters have now been considered "represented" and removed from consideration, the winner of the next automatic runoff is likely to be a beta candidate. This process continues until there are 5 winners. Using this method with the current example would likely result in 3 seats being awarded to alpha candidates, and 2 seats awarded to beta candidates.
To learn more about Proportional STAR, see the ElectoWiki page titled "Allocated Score".
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