Instant Runoff
With the instant runoff-method, we can find a winner. It is similar to the Coombs Method.
- Step 1: Voters assign their preferences to all candidates.
- Step 2: The candidate who has more than 50% of all first preferences wins. The tallying is over.
- Step 3: If there is no candidate with an absolute majority, the candidate with the least first preferences gets canceled.
- Step 4: Remaining candidates move up. The process continues with step 2.
Example
| Preference | A | A | B | B | C | C |
| Preference | B | C | A | C | A | B |
| Preference | C | B | C | A | B | A |
| Number of persons with this preference order | 6 | 0 | 5 | 2 | 5 | 3 |
No candidate has the absolute majority. Hence, eliminating all candidates with the least first preferences. In our case, this is candidate A.
B and C move up.
| Preference | B | C | B | B | C | C |
| Preference | C | B | C | A | B | B |
| Preference | – | – | – | – | – | – |
| Number of persons with this preference order | 6 | 0 | 5 | 2 | 5 | 3 |
Now, B has the most first preferences (13) and wins the election.
The problem with this method is that a voter can harm a candidate by giving it a good vote.
Example
| Preference | A | B | C |
| Preference | B | A | B |
| Preference | C | C | A |
| Number of persons with this preference order | 10 | 6 | 5 |
C gets eliminated
| Preference | A | B | B |
| Preference | B | A | A |
| Preference | |||
| Number of persons with this preference order | 10 | 6 | 5 |
B wins.
If three voters have the preferences (A>B>C) voting differently (C>A>B) according to the following table, they can make A win the election.
| Preference | A | B | C | C |
| Preference | B | A | B | A |
| Preference | C | C | A | B |
| Number of persons with this preference order | 7 | 6 | 5 | 3 |
B gets eliminated.
| Preference | A | A | C | C |
| Preference | C | C | A | A |
| Preference | ||||
| Number of persons with this preference order | 7 | 6 | 5 | 3 |
A wins instead of B, like in the first example.
