🔎 What This Note Reconsiders
This paper reevaluates measures of partisan symmetry proposed for practical use and clarified in Katz, King, and Rosenblatt (2020, American Political Science Review 114, 164–178). Attention centers on whether commonly used quantitative scores actually capture meaningful partisan fairness when applied to real-world vote patterns and redistricting decisions.
🧮 What the Analysis Does
- Uses elementary mathematical manipulation to inspect the formal properties of symmetry metrics.
- Tests those formal observations against recent voting patterns in three U.S. states: Utah, Texas, and North Carolina.
📐 Key Technical Findings
- The symmetry metrics exhibit surprising formal properties under basic algebraic scrutiny, properties that call their meaningfulness into question.
- Specific problems emerge when these metrics are applied to actual electoral data, producing counterintuitive or misleading scores in particular scenarios.
📍 Case Studies: Utah, Texas, North Carolina
- Utah: Identified concrete instances where standard scores fail to reflect practical partisan outcomes.
- Texas: Flagged situations in which metric behavior diverges from intuitive measures of fairness.
- North Carolina: Demonstrated additional anomalies that further illustrate limitations of current techniques.
📊 Which Metrics Are At Issue
- Mean–median score
- Partisan bias score
- The more general “partisan symmetry standard” as implemented in recent literature (see Katz, King, and Rosenblatt 2020)
⚠️ Why This Matters Now
- The observations raise major concerns about available techniques for producing quantitative scores of partisan symmetry just as the decennial redistricting process is underway.
- Policymakers, courts, and scholars relying on mean–median, partisan-bias, or partisan-symmetry standards should be aware that these tools can produce misleading conclusions in practice.
🧭 Bottom Line
Elementary mathematical critique plus empirical examples from three states together suggest caution in using current partisan symmetry metrics as definitive measures of electoral fairness during redistricting.
