Condorcet Method Demonstration
Pairwise Comparisons

Adapted from Rob Lanphier's Condorcet Method Program page. Here is the program's source code.

Candidates

Enter a comma-separated list of candidate numbers and candidate names.

SAMPLE
1, Alice
2, Betty
3, Carol
4, Danielle

Ballots

Enter a list of ballots, one per line. Each ballot should contain a list of candidate numbers in order of preference from most preferred to least preferred. The candidate numbers should be separated by ">" when the next candidate is less preferred, and "=" when the next candidate is equally preferred.

SAMPLES
2>3>1      # This person votes candidate 2 for first place.
2>1>3=4    # This person thinks candidates 3 and 4 tie for third place.
4>2        # This person votes for only first and second place.
2=3>1      # This person thinks candidates 2 and 3 tie for first place.
2 = 4 > 1  # It's okay to use spaces if you like.

It is not necessary to rank all candidates on every ballot. Unranked candidates are considered to be tied and rank just below all your ranked candidates. That is, 2>3 means 2>3>1=4. So, submit 2>3=1 if you think 2>3=1>4.

Now press the Submit button to see the Condorcet results.

Notes

If one candidate wins all the pairwise comparison tests, that candidate is the Condorcet winner. If there is no Condorcet winner, then some kind of tie-breaker may be necessary. The Condorcet tie-breaker method looks at each candidate's worst defeat and finds the one with the fewest votes against. The Copeland tie-breaker method looks at each candidate's win-loss-tie record and evaluates W+0.5T. Another tie-breaker method is to evaluate +W-L+0.5T.

In large-scale elections, you can collate ballots that match each other. If you wish to specify multiple ballots with the same ranking, precede the ranked list with a number and a colon to indicate the number of identical ballots with that ranking. 

COLLATED BALLOTS
40:3>2  # 40 ballots where C is preferred over B (and both implicitly over A and D)
9:2>3   #  9 ballots where B is preferred over C
15:1>2  # 15 ballots where A is preferred over B
16:2>1  # 16 ballots where B is preferred over A
20:1=2  # 20 ballots show no preference concerning A and B

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