Split-Ticket Propensity Index

Overview

This pillar quantifies the likelihood of split-ticket voting in U.S. congressional districts. It helps identify areas where voters might support a presidential candidate from one party and a congressional representative from another, a key factor in predicting close House races.

What It Does

The index analyzes historical election results, comparing presidential and congressional vote shares within each district over multiple cycles. It incorporates key demographic data, focusing on educational attainment and suburbanization trends, which are strong predictors of voter elasticity. The model also accounts for incumbency advantages and candidate quality to create a comprehensive score.

Why It Matters

In an era of high polarization, identifying the few remaining split-ticket districts offers a significant predictive edge. This pillar helps traders spot potential upsets and mispriced markets where national trends do not fully apply to local congressional races.

How It Works

First, we gather historical presidential and congressional election data for a specific district over the last three cycles. Second, we calculate the 'presidential-congressional vote gap' for each cycle. Finally, this historical gap is weighted by current demographic factors and incumbency status to produce a final propensity score.

Methodology

The index is a weighted score calculated as: (0.6 * Avg_Split_Rate_Last_2_Cycles) + (0.3 * Education_Polarization_Factor) + (0.1 * Incumbency_Bonus). The Split Rate is the absolute difference between the presidential and congressional two-party vote share. The Education Polarization Factor is derived from the district's percentage of college-educated voters relative to the national average.

Edge & Advantage

This provides a granular, district-level signal that counters the noise of national polling, identifying races where local dynamics will outweigh the presidential coattail effect.

Key Indicators

• Historical Vote Split

  high

  The percentage difference between presidential and congressional vote share in the district's past elections.

• Educational Polarization

  high

  The concentration of college-educated voters, a key demographic for ticket-splitting.

• Incumbency Strength

  medium

  Measures the advantage a sitting representative has, which can encourage split-ticket votes.

Data Sources

• Cook Political Report

  Provides district-level Partisan Voter Index (PVI) and historical election results.

• U.S. Census Bureau

  Source for demographic data, including educational attainment at the district level via the American Community Survey.

• Federal Election Commission (FEC)

  Official source for federal election campaign finance data and results.

Example Questions This Pillar Answers

• → Will the Republican Party win the U.S. House election in Maine's 2nd congressional district in 2024?
• → Will Jared Golden (D) win re-election in ME-02?
• → Will more than 10 congressional districts split their ticket in the 2024 U.S. election?

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