Analysis of Informal Voting, House of Representatives, 2010 Federal Election - Introduction

Updated: 30 May 2013

In every election a percentage of votes cast are likely to be informal. Informal votes are ballot papers that have not been filled out correctly in accordance with the requirements of the Commonwealth Electoral Act 1918 (the Electoral Act) and instructions on the ballot paper, and can therefore not be included in the count of votes leading to the election result. 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.

This paper provides a profile of informal voting at the 2010 House of Representatives election and presents results from the AEC's 2010 House of Representatives Informal Ballot Paper Survey. Statistics on informal voting at previous House of Representatives elections are also included to provide a historical context for the 2010 figures.

Analysis in this report includes discussion of proportions of informal votes and informality rates. Proportions of informal votes use the relevant total number of informal votes as the denominator, and are shown to one decimal place. Informality rates (proportions of total votes cast) use the relevant total number of votes cast as the denominator and are shown to two decimal places.

It should be noted that some figures relating to informal voting at previous elections have been revised to correct errors or inconsistencies in previously published reports. Footnotes have been added to tables to indicate where revisions have been applied. These revisions do not impact on any of the key findings made in previous reports.

In addition, changes to electorate boundaries as a result of redistributions will affect the comparability of data between elections.


Two main sources of data were used to analyse informal voting at the 2010 House of Representatives election. These were:

  • The AEC's Virtual Tally Room (VTR) for the 2010 federal election. The VTR provides national, state, divisional and polling place results for both the House of Representatives and the Senate.
  • The 2010 House of Representatives election Informal Ballot Paper Survey. This survey was completed by AEC staff, generally in AEC Divisional Offices, and provides counts of informal ballot papers in all polling places, for all divisions, according to specified categories. Counts for the following types of informal ballots are available from informal ballot paper surveys conducted for the 2001, 2004, 2007 and 2010 elections, allowing comparisons to be made between federal election years 1:
    • Blank ballots
    • Number '1' only ballots
    • Ticks and crosses
    • Non-sequential numbering
    • Marks and scribbles 2
    • Illegible numbering
    • Voter identified.

  1. Refer to Tables 1 and 2 for more information on the categories used in 2010, and how these relate to categories used in 2001, 2004 and 2007.
  2. Note that this does not mean ballots were informal because they bore writing, scribbles or other protest vote marks, but instead refers to ballot papers that were informal for another reason (usually because they lacked numbers) and had marks or scribbles.