These all tend to come under the term Ranked (or Preferential) Voting System as they are often associated with elections either at a national or regional level. There are other Voting Systems, notably Range Voting. Many electoral voting systems are not particularly fair but are easy to explain to the public. So ease of interpretation of the sytem used wins over a fair election!
A Condorcet Method is "any election method that elects the candidate that would win by majority rule in all pairings against the other candidates, whenever one of the candidates has that property". It is often useful to know if a particular ranking algorithm or election method is a Condorcet Method.
This is our preferred ranking algorithm. It passes more tests of fairness than the others and is a Condorcet method (unlike the others).
This is a ranking algorithm based on Ranked Pairs but with a slight twist. While it is time consuming to calculate by hand but it very easy to implement in software.
There are a few online discussions regarding the merits of various scoring systems, there are some proponents of using raw scores but without rigorous training or a consistent approach to judging, raw scores are not recommended. Using raw scores does not satisfy the requirements of a Condorcet Method.
Borda Count deals with Raw Rankings. We and other studios used this approach but it has drawbacks. It is not a Condorcet Method.
The Skating System has been in use since 1937 is possibly the most widely used scoring system. In Ballroom there can be as many as 10 different dances and this system aims at picking the overall best performers. However it is not a Condorcet Method and so in less 2% of cases this does not happen! (Refer to statistical analysis performed by Xavier Mora, Professor of Mathematics, Barcelona Universty).
- Used by Dance Sport and the World Salsa Federation
- Odd number of judges 3, 5, 7, 9 etc to reduce likelihood of ties.
- In preliminary rounds scoring is done at the end of the round not at the end of each heat and judges must mark a specific number of competitors across all heats.
- The multi-dance aspect does not satisfy the Ostrogorski Paradox as mentioned in Professor Mora's paper.
The World Swing Dance Council uses Relative Placement and it was used at the World Modern Jive Championships in the UK in 2014. It is similar to the Skating System but with a couple of minor differences. Based on the same principles.
- 3 options for judging competitors in preliminary rounds: selected, not selected, alternate.
- Judges do not have to mark a specified number of competitors to go through nor do they have to select a certain number across all heats.
There are many discussions regarding the Skating System and Relative Placement however few people (including judges) understand the finer details and how to determine the fairness of a scoring system. Neither are Condorcet Methods but they are so entrenched in their respective dance styles that any change is unlikely. It is hardly surprising that they are not listed as standard voting systems in mainstream or academic articles. An advantage is that they can be calculated using just pencil and paper, however this is now their weakness as computers have meant that fairer systems can now be used with ease.