Simulating STV hand-counting by computers considered harmful: A.C.T

Abstract

We outline various ways in which the single transferable vote-counting (STV) algorithm used by the Australian Capital Territory (ACT) differs from the basic STV algorithm as well-known from social choice theory. Most of these differences were instituted to make it easier and faster to determine the result of counting around 300,000 ballots by hand. We give small examples to show how such “simplifications” can lead to counter-intuitive results. We also argue that these “simplifications” significantly complicate computer implementation and general understanding of the counting procedure, especially in a mathematical sense. We then demonstrate the strange effects of these “simplifications” in real-world computer counted election results which were published by ACT Elections. It is imperative that electoral commissions begin the legislative processes required to replace their existing “simplified” STV with “unsimplified” STV. Show more