{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/risk-limiting-audits-by-stratified-union","title":"Risk-Limiting Audits by Stratified Union-Intersection Tests of Elections (SUITE)","arxiv_id":"1809.04235","date":"2018-09-12","proceeding":null,"authors":["Kellie Ottoboni","Philip B. Stark","Mark Lindeman","Neal McBurnett"],"abstract":"Risk-limiting audits (RLAs) offer a statistical guarantee: if a full manual tally of the paper ballots would show that the reported election outcome is wrong, an RLA has a known minimum chance of leading to a full manual tally. RLAs generally rely on random samples. Stratified sampling--partitioning the population of ballots into disjoint strata and sampling independently from the strata--may simplify logistics or increase efficiency compared to simpler sampling designs, but makes risk calculations harder. We present SUITE, a new method for conducting RLAs using stratified samples. SUITE considers all possible partitions of outcome-changing error across strata. For each partition, it combines P-values from stratum-level tests into a combined P-value; there is no restriction on the tests used in different strata. SUITE maximizes the combined P-value over all partitions of outcome-changing error. The audit can stop if that maximum is less than the risk limit. Voting systems in some Colorado counties (comprising 98.2% of voters) allow auditors to check how the system interpreted each ballot, which allows ballot-level comparison RLAs. Other counties use ballot polling, which is less efficient. Extant approaches to conducting an RLA of a statewide contest would require major changes to Colorado's procedures and software, or would sacrifice the efficiency of ballot-level comparison. SUITE does not. It divides ballots into two strata: those cast in counties that can conduct ballot-level comparisons, and the rest. Stratum-level P-values are found by methods derived here. The resulting audit is substantially more efficient than statewide ballot polling. SUITE is useful in any state with a mix of voting systems or that uses stratified sampling for other reasons. We provide an open-source reference implementation and exemplar calculations in Jupyter notebooks.","url_abs":"http://arxiv.org/abs/1809.04235v1","url_pdf":"http://arxiv.org/pdf/1809.04235v1.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"risk-limiting-audits-by-stratified-union","repo_url":"https://github.com/pbstark/CORLA18","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":null},{"paper_slug":"risk-limiting-audits-by-stratified-union","repo_url":"https://github.com/benjaminfuller/arlo","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":{"status":"ok"}},{"paper_slug":"risk-limiting-audits-by-stratified-union","repo_url":"https://github.com/votingworks/arlo","is_official":0,"mentioned_in_paper":0,"mentioned_in_github":1,"framework":"none","reach":{"status":"unanswered"}}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}