Finding Data for Precinct Deviation Analysis (PDA)

CitizensOversight (2026-06-22) RaymondLutz

This Page: copswiki.org/Common/M2058

More Info: ElectionIntegrity, ElectionAudits, PrecinctDeviationAnalysis

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Finding Data for Precinct Deviation Analysis (PDA)

Precinct Deviation Analysis (PDA) compares the partisan makeup of each precinct with the actual votes cast in a partisan contest.

To do this, we need two types of data:

• Election results by precinct.
• Voter registration by party for each precinct.

The challenge is finding these datasets and making sure they correspond to the same election period.

What We Need

1. Precinct Election Results

For the election being studied, we need vote totals by precinct for each candidate.

The ideal file includes:

• County
• Precinct
• Candidate
• Party
• Votes

Many states publish this data directly. Sometimes it is available from the Secretary of State. Other times it must be collected county by county.

2. Voter Registration by Party

This is often the harder dataset to find.

We need registration counts for each precinct, preferably from just before the election.

The ideal data tells us how many voters in each precinct were:

• Democratic
• Republican
• Independent / Unaffiliated
• Other parties

Even better is obtaining the actual voter registration file. If that is available, we can calculate the precinct totals ourselves, verify the results, and perform additional analyses later.

Your Mission

See what data is available in your state.

Questions to answer:

1. Are precinct-level election results available?
2. Are precinct-level voter registration statistics available?
3. Is a statewide voter file available?
4. What dates are available for voter registration snapshots?
5. Do the precinct names and identifiers appear compatible between the election results and registration data?

What To Collect

When you find a useful dataset, please record:

• Source agency
• URL
• File name
• Publication date
• Election covered
• Notes about what the file contains

Download the files whenever possible.

Helpful Tips

• Start with the Secretary of State or State Election Office.
• Search for "election results", "voter registration statistics", "voter file", and "precinct data".
• County election offices sometimes publish data that is not available from the state.
• Historical voter registration snapshots are often more valuable than current registration numbers.
• If you find voter-level registration data, that may be even better than pre-computed precinct statistics.

Goal

The ultimate goal is to assemble a statewide dataset containing:

• Precinct election results.
• Precinct voter registration by party.

Once those datasets are available, PDA can compare expected voting patterns with actual election results and identify precincts that deserve closer examination.

Why This Matters

Political party affiliation is one of the strongest predictors of voting behavior. PDA uses the partisan composition of each precinct to estimate how voters are expected to divide between the major-party candidates.

When a large number of precincts are analyzed together, consistent patterns emerge. Precincts that differ substantially from those patterns may deserve additional investigation. PDA does not prove that anything is wrong; rather, it helps identify precincts and jurisdictions that merit closer examination.