How many votes should you cast when you are voting in a contest which has multiple candidates? Consider a ballot with 5 candidates for 4 spots, where you can pick any 4 of 5. You're wildly enthusiastic about 2 candidate, neutral on 1 candidates, and opposed to 2 candidates. Here are your choices:
1. Undervote the ticket, casting only 2 votes for your favorites and leaving 3 votes behind.
2. Undervote the ticket, casting votes for your favorites and the neutral, leaving 2 votes behind.
3. Cast 4 votes, leaving none behind, and choosing one of the candidates you are opposed to to round out the ballot.
The strategy is called "bullet voting", and it has some pros and cons which are neatly spelled out in this 2005 blog post from Larry Davidson.
So, to bullet-vote or not? The choice depends entirely on which scenario you think is more probable. If the race for fourth place is between your two favorite candidates, you should bullet-vote. If the race for fourth place is between your second choice and someone you strongly dislike, you should not bullet-vote. Maybe it’s not how they would handle it on Numb3rs, but math can’t give you a definite answer here.
Bullet voting is also known as "plunking". The general case of voting systems being gamed by strategic voters is more common than you'd expect, since it can give a coordinated minority the ability to decide an election over a disorganized majority.
