Auditing Indian elections

Abstract

Electronic Voting Machines (EVMs) used in the 2019 General Elections in India were fitted with printers to produce Voter-Verifiable Paper Audit Trails (VVPATs). VVPATs allow voters to check whether their votes were recorded as they intended. However, confidence in election results requires more: VVPATs must be preserved inviolate and then actually used to check the reported election result in a trustworthy way that the public can verify. A full manual tally from the VVPATs could be prohibitively expensive and time-consuming; moreover, it is difficult for the public to determine whether a full hand count was conducted accurately. We show how Risk-Limiting Audits (RLAs) can provide high confidence in Indian election results. Compared to full hand recounts, RLAs typically require manually inspecting far fewer VVPATs when the outcome is correct, and are much easier for the electorate to observe in adequate detail to determine whether the result is trustworthy. We show how to apply two RLA strategies, ballot-level comparison and ballot polling, to General Elections in India. Our main result is a novel method for combining RLAs in constituencies to obtain an RLA of the overall parliamentary election result.