Research Methodology

Transparent, rigorous analysis of congressional data from authoritative sources with full methodological disclosure.

Research Approach

Our analysis employs a comprehensive, data-driven approach to examine congressional accountability and electoral competition. We prioritize official government sources, established research institutions, and transparent methodologies to ensure accuracy and reproducibility.

Core Principles

Source Verification
All data points are traced to primary sources with full citation and verification of authenticity.
Methodological Transparency
All calculations, transformations, and analytical decisions are documented and reproducible.
Bipartisan Analysis
Analysis avoids partisan interpretation, focusing on institutional metrics rather than policy outcomes.
Peer Review
Findings are reviewed by academic experts in political science and public policy.

Data Sources

Primary Government Sources

Federal Election Commission (FEC)
Primary

Official election results, candidate filings, campaign finance reports, and expenditure data

Coverage: 1976-presentVisit
Clerk of the U.S. House of Representatives
Primary

Historical election statistics, member biographical data, and voting records

Coverage: 1789-presentVisit
U.S. Senate Historical Office
Primary

Senate election results, biographical data, and institutional records

Coverage: 1789-presentVisit
Congressional Budget Office (CBO)
Primary

Fiscal analysis, budget projections, and economic impact assessments

Coverage: 1975-presentVisit

Research Organizations

Ballotpedia
Secondary

Comprehensive election database and candidate information

Coverage: 2007-presentVisit
Center for Responsive Politics (OpenSecrets)
Secondary

Campaign finance analysis and lobbying data

Coverage: 1990-presentVisit
Gallup Organization
Secondary

Public opinion polling and congressional approval ratings

Coverage: 1974-presentVisit
Pew Research Center
Secondary

Political attitudes research and demographic analysis

Coverage: 2004-presentVisit

Key Metrics Definitions

Incumbent Reelection Rate

Definition

Percentage of incumbents seeking reelection who successfully win their race

Formula

(Incumbents Reelected ÷ Incumbents Seeking Reelection) × 100

Methodology

Based on general election results; primary defeats count as reelection failures

Notes

Calculated separately for House and Senate; excludes members who retire or seek other office

Split-Ticket Voting

Definition

Percentage of possible mixed-party election outcomes in presidential election years

Formula

Districts/States with different party control between presidential and congressional races

Methodology

Compares presidential winner by district/state to congressional delegation party control

Notes

Measured only in presidential election years; indicates cross-pressured electorates

Congressional Approval Rating

Definition

Percentage of Americans who approve of the job Congress is doing

Formula

Monthly polling averages aggregated to annual figures

Methodology

Random sampling of U.S. adults via telephone and online interviews

Notes

Based on Gallup polling with margin of error ±3-4 percentage points

Campaign Spending Differential

Definition

Ratio of incumbent to challenger average campaign receipts

Formula

Average Incumbent Receipts ÷ Average Challenger Receipts

Methodology

Calculated per election cycle; excludes unopposed races

Notes

Based on FEC reports; includes all receipts through election day

Legislative Productivity

Definition

Number of substantive laws enacted per Congress

Formula

Count of public laws excluding ceremonial and administrative measures

Methodology

Manual review of each law to exclude commemorative resolutions and routine reauthorizations

Notes

Based on Congressional Research Service categorization of 'substantive' legislation

Data Collection Methods

Automated Collection

Where possible, we use automated systems to collect data from official APIs and structured databases. This includes:

  • FEC campaign finance data via their REST API
  • Congressional voting records from Congress.gov
  • Election results from state election offices

Manual Verification

All automated collection is supplemented by manual verification:

  • Cross-referencing against multiple sources
  • Spot-checking random samples for accuracy
  • Reviewing edge cases and anomalies
  • Validating calculations against published totals

Historical Data Reconstruction

For historical periods predating digital records, we rely on:

  • Official government publications and archives
  • Academic datasets with established provenance
  • Newspaper archives for election results verification
  • Multiple source triangulation for contested figures

Quality Assurance Process

Multi-Stage Validation

  1. Source Authentication: Verify all data comes from authoritative, official sources
  2. Cross-Reference Check: Compare data across multiple independent sources when available
  3. Calculation Review: Independent verification of all mathematical operations and formulas
  4. Temporal Consistency: Ensure data series are consistent across time periods and methodology changes
  5. Expert Review: Academic and policy expert review of methodology and findings
  6. Public Disclosure: Full methodology publication for external scrutiny and replication

Error Detection and Correction

We maintain rigorous error detection protocols:

  • Automated range checks for statistical outliers
  • Trend analysis to identify potential data breaks
  • Regular audits of calculation accuracy
  • Public correction process for identified errors

Limitations and Caveats

Data Limitations

  • Historical Completeness: Some early data may be incomplete or estimated based on available records
  • Definitional Evolution: Some metrics have evolved over time as reporting standards changed
  • Sampling Variation: Opinion polling data subject to sampling error and methodological differences
  • Reporting Delays: Most recent data may be preliminary pending final official reports

Analytical Limitations

  • Correlation vs. Causation: Statistical relationships do not necessarily imply causal relationships
  • Predictive Limitations: Historical trends may not predict future outcomes
  • Context Dependency: Metrics may be influenced by external factors not captured in the analysis
  • Aggregation Effects: National averages may obscure important regional or demographic variations

Scope Limitations

  • Federal Focus: Analysis limited to federal elections and institutions
  • Quantitative Emphasis: Prioritizes measurable indicators over qualitative assessments
  • Institutional Perspective: Focuses on systemic rather than individual-level factors

Updates and Revisions

Update Schedule

Data and analysis are updated on a regular schedule:

  • Quarterly: Routine data updates and minor corrections
  • Post-Election: Major updates following federal elections
  • Annual: Comprehensive methodology review and validation
  • Ad-hoc: Corrections for identified errors or significant new data availability

Version Control

All updates are tracked using semantic versioning:

  • Major versions: Significant methodology changes or new data series
  • Minor versions: Data additions or minor methodology refinements
  • Patch versions: Error corrections and clarifications

Change Documentation

All changes are fully documented with:

  • Detailed changelog with rationale for modifications
  • Impact assessment on existing analyses
  • Backward compatibility notes where applicable
  • Public notification of significant changes