In every election, it is likely that a small proportion of the votes cast will not meet the specified voting requirements and will therefore be deemed informal. Levels of informal voting can provide an indication of people's engagement with (and understanding of) the electoral process and, together with enrolment participation rates and measures of turnout, are therefore a key indicator of democratic health.
The paper provides a profile of informal voting at the 2010 House of Representatives election and presents results from the Australian Electoral Commission's (AEC) 2010 House of Representatives Informal Ballot Paper Survey. Data on informal voting at previous House of Representatives elections is also included to provide a historical context for the 2010 figures. Results from the Informal Ballot Paper Survey – and, in particular, findings relating to assumed unintentional and intentional informal voting – show that a challenge remains to maximises electors' potential participation in the electoral process.
The national informality rate at the 2010 House of Representatives election was substantially higher than that recorded at the 2007 House of Representatives election and is the highest recorded since the 1984 House of Representatives election. At the state and territory level, the highest informality rates were in New South Wales and the Northern Territory, while the lowest informality rates were in Victoria and Tasmania.
The 10 divisions with the highest rates of informal voting at the 2010 House of Representatives election were Blaxland, Fowler, Watson, Chifley, McMahon, Werriwa, Greenway, Barton, Reid, and Parramatta.
More than half of all informal ballots in 2010 had incomplete numbering or were totally blank. This was also the first federal election since informal ballot paper surveys began where the proportion of blank ballots was higher than the proportion of number '1' only ballots.
While it appears that most informal voting continues to be unintentional, there was a substantial increase in assumed intentional informal voting (in particular, blank ballots) at the 2010 House of Representatives election.
As has been the case in previous studies, English language proficiency and the numbers of candidates on ballot papers continue to be significant factors associated with the level of informal voting (or, in the case of candidate numbers, changes in the level of informal voting).
Analysis of the potential impact of differences between state or territory electoral systems and the federal electoral system on levels of informality provided mixed results. Higher informality rates for ballots with incomplete numbering in New South Wales and Queensland may be influenced in part by the optional preferential voting provisions for the lower house in these states. However, both of the jurisdictions with partial preferential voting had informality rates for incompletely numbered ballots that were below the national average, and two of the four states that allow ticks and crosses as a first preference for lower house elections had informality rates for ticks and crosses below the national average.
There did not appear to be a clear pattern between informality rates within states or territories and the proximity of the most recent state or territory election. Of the two states that held a state election in 2010, one (Tasmania) had the lowest informality rate while the other (South Australia) had the third highest rate.
There are many factors that could influence a voter to intentionally or unintentionally cast an informal vote and it is not possible, in many cases, to accurately quantify or even separately identify the impact these factors might have. Of those factors identified as significant influences on informal voting at previous House of Representatives elections, English language proficiency and the number of candidates appear to be the strongest predictors of informality rates (or changes in informality rates) in 2010. Analysis relating to differences between state and territory electoral systems and the federal system provided mixed results, suggesting that other factors were more significant influences on informality in 2010.