Voting Rights Data Analysis

Voting Rights data analysis is often recommended as an early step in any districting or redistricting process, to ensure that the plan will meet the requirements of  §2 of the federal  Voting Rights Act of 1965.  This section of the Act prohibits “minority vote dilution” – any practice that impairs the ability of minority voters to elect candidates of their choice on equal footing with non-minority voters.

The occurrence of minority vote dilution can be assessed for a given jurisdiction by performing a “racially polarized voting” analysis.  Since public voting records do not indicate who voted for each candidate, or the racial category of any registered voter, the racial breakdown of any candidate’s support is not directly known.

However, most courts have accepted inferential analyses of precinct-level electoral data.  The two commonly accepted techniques are “homogenous precincts” analysis and “bivariate ecological regression” analysis.  Ideally, each analysis should include several election cycles to see if polarized voting is structural – always there at a certain level – and not just the result of an occasional lost election.

The fact that racially-polarized voting exists in some areas should neither surprise nor alarm anyone.  Minority race, language or origin residents tend to coalesce around issues and support candidates of interest to them -- choices that sometimes differ from those of non-minority voters.  The data analysis looks at how often the candidates of choice of minority voters are overwhelmed by non-minority bloc voting.


Pinal County, AZ – Demographic and election analysis services in connection with legislatively ordered changes to the number of Supervisor districts, 2009.

City of Phoenix, AZ – Principal consultant for City Council redistricting process, 2002.

Yuma County, AZ – Analysis of retrogression of voting strength of voting-age minority populations in the supervisorial and community college districts adopted in 1995; response to request for additional pre-clearance review information from the U.S. Department of Justice, Civil Rights Division, 1996.

Jennings, Strouss & Salmon law firm – In Smith vs. Salt River Project (CIV94-0118 PHX SMM), U. S. District Court – engaged to assist SRP’s legal team in their defense of the utility against a lawsuit charging that SRP’s method of electing board members, based upon land ownership, was in violation of the federal Voting Rights Act; provided demographic and statistical analysis of census data and voting behavior, 1995.

Lewis & Roca law firm, Phoenix AZ – Statistical analysis of relationship between race and political party registration in Arizona, 1995.  

Arizona State Senate – Redistricting technical services in connection with state’s request to U.S. Department of Justice for reconsideration of the adopted, but not precleared, legislative districts plan, 1993; and  redistricting technical consulting services to the Senate Majority Caucus in 1992.