An analysis of New South Wales electronic vote counting
This work addresses critical software flaws in electoral systems, impacting election integrity and fairness for voters and candidates in New South Wales, though it is incremental as it builds on known issues with randomness in vote counting.
The researchers identified a software error in New South Wales' electronic vote counting system that significantly reduced candidate Rina Mercuri's winning probability from 91% to about 10% in the 2012 local government elections, and later found two new errors in the 2016 elections after the initial correction.
We re-examine the 2012 local government elections in New South Wales, Australia. The count was conducted electronically using a randomised form of the Single Transferable Vote (STV). It was already well known that randomness does make a difference to outcomes in some seats. We describe how the process could be amended to include a demonstration that the randomness was chosen fairly. Second, and more significantly, we found an error in the official counting software, which caused a mistake in the count in the council of Griffith, where candidate Rina Mercuri narrowly missed out on a seat. We believe the software error incorrectly decreased Mercuri's winning probability to about 10%---according to our count she should have won with 91% probability. The NSW Electoral Commission (NSWEC) corrected their code when we pointed out the error, and made their own announcement. We have since investigated the 2016 local government election (held after correcting the error above) and found two new errors. We notified the NSWEC about these errors a few days after they posted the results.