Instant Runoff

Ranked ballots and a strange paradox

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• IRV eliminates the last-placed candidate and transfers ballots.
• It can fail monotonicity: more support can make a candidate lose.
• It can eliminate a Condorcet winner with few first preferences.

Steps

1. Eliminate and transfer
2. Watch the count
3. Run the count
4. More support, fewer wins?
5. Burlington, 2009
6. Transfers decide
7. A cycle in disguise