Analysis of Informal Voting, House of Representatives, 2010 Federal Election - Key findings

Updated: 30 May 2013
  • In the 2010 House of Representatives election there was a national informality rate of 5.55 percent. This was the highest informality rate recorded since 1984, and represents a substantial increase from the 3.95 percent recorded at the 2007 House of Representatives election.
  • The 10 divisions with the highest rates of informal voting were all in Sydney. The top 10 divisions in 2010 were: Blaxland (14.06 percent); Fowler (12.83 percent); Watson (12.80 percent); Chifley (11.16 percent); McMahon (10.84 percent); Werriwa (10.35 percent); Greenway (10.27 percent); Barton (9.82 percent); Reid (8.80 percent); and Parramatta (8.65 percent).
    • Eight of the top 10 informality divisions in 2010 were also in the top 10 for 2007, while nine were in the top 10 for 2004.

Categories of informal ballots

  • More than half of all informal ballots in 2010 had incomplete numbering or were totally blank (27.8 percent with a number '1' only, 2.6 percent with other forms of incomplete numbering and 28.9 percent blank). This was the first House of Representatives election since informal ballot paper surveys began where the proportion of blank ballots was higher than the proportion of number '1' only ballots.

Blank ballots

  • While more than a quarter of all informal votes cast in each state and territory in 2010 were blank, blank ballots still comprise less than two (1.60) percent of all votes cast.
  • The highest proportions of blank ballots were cast by voters in Tasmania (34.1 percent of all informal ballots) and South Australia (32.4 percent). These states also recorded the highest proportions of blank ballots at the 2007 House of Representatives election (29.3 and 26.9 percent, respectively).
  • Nationally the rate of blank ballots doubled between the 2007 and 2010 House of Representatives elections, from 0.79 percent of all votes cast in 2007 to 1.60 percent of all votes cast in 2010.
  • The states with the highest rates of blank ballots were New South Wales (1.84 percent of all votes cast) and South Australia (1.77 percent), while the lowest rates of blank votes were cast by voters in the Australian Capital Territory (1.39 percent of all votes cast) and Tasmania (1.38 percent).

Incomplete ballots

  • The proportion of informal ballots with incomplete numbering decreased from 34.6 percent in 2007 (30.1 percent with a number '1' only) to 30.4 percent in 2010 (27.8 percent with a number '1' only).
  • The highest proportions of ballots with incomplete numbering were in New South Wales (35.1 percent of all informal ballots in 2010) and Queensland (34.7 percent). While this may, in part, be influenced by the use of optional preferential voting for state elections in New South Wales and Queensland, other factors may also apply.
  • The informality rate for ballots with incomplete numbering increased from 1.37 percent of all votes cast in 2007 to 1.69 percent of all votes cast in 2010.

Assumed unintentional and intentional informality

  • As it is not possible to determine the true intent of voters casting informal ballots, analysis in this report refers to assumed unintentional and assumed intentional informality.
    • Ballot papers with incomplete numbering, non-sequential numbering, ticks and crosses and those where the voter had been identified are assumed to be unintentionally informal (i.e. it is assumed that all voters with ballot papers in these categories intended to cast a formal vote).
    • All other informal ballot papers (including blank ballots and those with scribbles, slogans and other protest vote marks) are assumed to be intentionally informal (i.e. it is assumed that these voters intended to cast an informal vote).
  • Levels of assumed unintentional informal voting continue to be higher than levels of assumed intentional informal voting. However, the proportion of assumed unintentional informal ballots has decreased from 62.5 percent of all informal ballots in the 2007 House of Representatives election, to a little over half of all informal ballots (51.4 percent) in 2010.
  • The highest proportions of assumed unintentional informal votes were cast by voters in New South Wales (58.8 percent of all informal ballots) and the Northern Territory (54.8 percent). The highest proportions of assumed intentional informal ballots were cast by voters in Tasmania (64.7 percent of all informal ballots) and Victoria (57.5 percent).
  • The rate of assumed unintentional informal voting increased from 2.47 percent of all votes cast in the 2007 House of Representatives election to 2.85 percent of all votes cast in the 2010 House of Representatives election. However, the 2010 assumed unintentional informality rate is lower than that recorded at either the 2001 (3.18 percent of all votes cast) or 2004 elections (3.21 percent).
  • At the state and territory level, New South Wales and the Northern Territory recorded the highest assumed unintentional informality rates in 2010 (4.02 percent and 3.39 percent of all votes cast, respectively) as well as the highest intentional informality rates (2.81 and 2.80 percent, respectively).
  • The lowest assumed unintentional informality rates were in Tasmania (1.43 percent of all votes cast) and Victoria (1.91 percent), while the lowest assumed intentional informality rates were in Western Australia (2.54 percent of all votes cast), Victoria and the Australian Capital Territory (each 2.58 percent).

Factors influencing informal voting

  • This report analyses the impact of English language proficiency, the number of candidates on the ballot paper, differences between state/territory and federal electoral systems and proximity to other electoral events) on informal voting. However, there are likely to be many other factors that might also influence levels or patterns of informality. The nature of a secret ballot means it is difficult to accurately determine what influences a voter to intentionally or unintentionally cast an informal vote.

English language proficiency

  • As was the case in previous elections, analysis of 2010 election results showed a statistically significant link between English language proficiency and informality rates. Divisions where higher proportions of the population have lower levels of English language proficiency are likely to have higher levels of informal voting.
  • Five out of the 10 divisions with the highest informality rates at the 2010 House of Representatives election also had the five highest proportions of persons who, at the 2006 Census of Population and Housing, indicated that they did not speak English well, or did not speak English at all.

Number of candidates

  • The number of candidates on ballot papers for the 2010 House of Representatives election ranged from three candidates (in the divisions of Canberra, Barton, Bradfield, Mackellar, Werriwa and Braddon) to 11 candidates (in the divisions of Bennelong and Greenway). The 10 divisions with the highest levels of informality in the 2010 House of Representatives election included divisions with the highest (Greenway) and lowest (Barton) numbers of candidates.
  • The 2010 election saw increasing informality rates in each state and territory combined with decreases (or, in the case of the Northern Territory, no change) in the average number of candidates.
  • Multivariate analysis shows that the proportion of the population with lower levels of English language proficiency is a stronger predictor of informality rates at the 2010 House of Representatives election than candidate numbers. However, changes in candidate numbers between the 2007 and 2010 elections were a stronger predictor of changes in informality.

Differences between electoral systems and proximity between electoral events

  • Analysis of the impact that differences between electoral systems and the proximity between electoral events might have on informality rates provided mixed results, and suggests that other factors were more significant at the 2010 federal election:
    • Of the two states that use optional preferential voting for state lower house elections (New South Wales and Queensland), both had above average informality rates for ballots with incomplete numbering (i.e. ballots with a number '1' only as well as other incompletely numbered ballots).
    • Of the two jurisdictions that use partial preferential voting for lower house elections (Tasmania and the Australian Capital Territory), both had below average informality rates for ballots with incomplete numbering.
    • Of the four states that provide for ticks or crosses to be accepted as valid first preferences in state lower house elections (New South Wales, Victoria, Queensland and South Australia), New South Wales and South Australia had informality rates for ballots with ticks and crosses that were above the national average, while Queensland and Victoria had informality rates for ballots with ticks and crosses that were below the national average.