PRSTV can be used to determine the most preferred option among many possible options.
What the voter does is to rank options in the order of preferences. When voting is closed, first preference votes are counted. If no option has more than 50% support then the second preference of votes cast for the least popular option - or hopelessly unpopular options - are redistributed. The procedure is repeated until one option receives >50% of the votes or all of the preferences are used up - in which case the most popular option at that stage wins.
In the following example, nine voter vote for their favourite colour form the options Red, Green and Blue:
| Voter | Preference |
|---|---|
| Voter A | Red, then Green |
| Voter B | Red, then Blue |
| Voter C | Green, then Red |
| Voter D | Red, then Green |
| Voter E | Red, then Green |
| Voter F | Blue, then Green |
| Voter G | Green, then Red |
| Voter H | Green, then Blue |
| Voter I | Blue, then Green |
- Round 1: Red = 4, Green = 3, Blue = 2
- => Redistribute 2nd preference of votes for Blue
- Round 2: Red = 4, Green = 5
- Result: Green is the most preferred.