Which statement best describes the efficiency gap in election analysis?

• A. A measure of how many seats each party wins
• B. A measure of how evenly wasted votes are across parties, used to detect gerrymandering
• C. The difference in turnout between districts
• D. The total number of votes cast nationwide

Answer: (B)

The efficiency gap looks at wasted votes to see how fairly votes translate into seats. In each district, votes for the winning candidate beyond the smallest margin needed to win are considered wasted for that party, and all votes for the losing party are wasted as well. When you sum wasted votes for both parties across all districts and compare the totals, the difference, divided by the total number of votes cast, gives the efficiency gap. If one party has many more wasted votes than the other—often because district boundaries concentrate that party’s voters in a few districts while spreading the opponent’s voters across many—there’s a larger efficiency gap, which can indicate partisan gerrymandering. This concept isn’t about how many seats a party wins, turnout differences between districts, or the total votes cast nationwide; it specifically measures how evenly wasted votes are and uses that to infer potential gerrymandering.