 where p represents the probability that Sally’s vote is decisive, \([V(D) - V(R)]\) represents (in monetary terms) the difference in the expected value of the two candidates, and C represents the opportunity cost of voting. In short, the value of her vote is the value of the difference between the two candidates discounted by her chance of being decisive, minus the opportunity cost of voting. In this way, voting is indeed like buying a lottery ticket. Unless \(p[V(D) - V(R)] &gt; C\), then it is (given Sally’s stated goals) irrational for her to vote.