We have improved our sampling procedures each year to try and control for the impact of jurisdiction size as measured by the total number of registered voters. Much of the credit for the sampling methodology and sampling weights lies with Jay Lee (Reed ’19), currently a research associate at the Sightline Institute’s democracy program
The 2018 and 2019 LEO Surveys were significant learning opportunities to develop best practices for sampling, surveying, and producing accurate statistical estimates across the “complex quilt” (Brown, Hale, and King 2020) of American elections and election administration.
Since 2019, we have developed our sampling frame by building off of the most recent EAVS survey, and then scraping data from secretary of state websites or similar sites, state by state. We made a series of edits to this list of jurisdictions to create proper entries for each local jurisdiction that included a local administrator responsible for election administration. This resulted in a sampling frame with 7,834 local jurisdictions. We drew a sample of n = 3,000 from this list using the random systematic sampling method, with inclusion probabilities proportional to the number of registered voters in each jurisdiction. This ensured that all of the largest jurisdictions (> 15,000 registered voters) were included in the sample, and we collected a representative sample of jurisdictions of smaller sizes.
In 2022 and 2023, we drew an oversample of majority-minority jurisdictions, which increased our sample by approximately 120.
Final sample weights are based on the design weights from our sampling method (i.e. smaller jurisdictions, with less chance of being sampled, received higher weights). The weights are trimmed to avoid individual small jurisdictions having inordinately large weights and post-stratified our responses to ensure the weighted proportion of responses in each size bin (0 to 5,000 registered voters; 5,001 to 25,000; 25,001 to 100,000; 100,001 to 250,000; more than 250,000) is equal to the overall proportion of each size bin in the full LEO population.
A detailed discussion of the sampling and weighting methodology is provided by Lee and Gronke (2020).