What is Margin of victory?

Margin of victory refers to the percentage point lead that a candidate or party has in an election over the candidate or party ranked second. For example, if Candidate A wins an election with 35% of the vote and Candidate B, who finishes in the second place, wins 30% percent of the vote, the winner's margin of victory is five percentage points. Margins of victory can be used to measure electoral competitiveness, political party or candidate strength, and, indirectly, the popularity of a particular policy or set of policies.