On Saturday 19 March 2005, electors in Werriwa, New South Wales cast their ballots in a federal by-election; 16 candidates nominated. Overall informality was 13.15 percent, an increase from 7.98 percent at the 2004 Federal election.
Every election has some degree of informal votes cast. The AEC has published several research papers on informality. The Informal Vote Survey – House of Representatives 2001 Election  provided an analysis of informality in Australia, reviewing the sociological factors that are high predictors of informality. In 2005, the AEC also published a paper: Analysis of Informal Voting During the House of Representatives 2004 Election that examined possible factors that may have contributed to the increase in informality levels between 2001 and 2004.  More on the history and background on formal voting requirements and informality can also be found in the Electoral Backgrounder Number 18 on Informal Voting published by the AEC .
There is a mandatory preferential voting system in the federal election for the House of Representatives, by which a ballot will be considered informal if:
These ballots do not count towards any candidate, and are counted separately. For analytical purposes, the AEC sorts and categorises informal ballot papers into several categories for analysis.
Since federation there have been 141 by-elections. It is generally accepted that by-elections have unusual outcomes. Newman and Bennett claim that by-elections are held in such different and unusual circumstances that none can be regarded as typical . One common outcome of by-elections is a low voter turnout compared to general elections. Since 1924 the average by-election turnout has been 87.7% compared to 94.5%. Another phenomena in by-elections are often an increase in informality rates. While some of the by-election informality rates do not appear to be abnormally high, it is important to observe the rate relative to the base rate (the federal election).
The following table identifies the last 5 by-elections and the informality rate.
|By Election||Date||Federal Election||Federal Election Informality%||By-Election Informality%||Percentage Point Change|
|Holt||6 Nov 1999||3 Oct 1998||4.5||7.2||2.7|
|Isaacs||12 Aug 2000||3 Oct 1998||3.6||8.2||4.6|
|Ryan||17 Mar 2001||3 Oct 1998||2.3||3||0.7|
|Aston||14 Jul 2001||3 Oct 1998||2.8||5.8||3.0|
|Cunningham||19 Oct 2002||10 Nov 2001||4.8||7.7||2.9|
|Werriwa||19 Mar 2005||9 Oct 2004||8.0||13.1||5.1|
This paper seeks to analyse the informal vote in Werriwa, and identify factors that may have influenced or may explain informality levels during the March 2005 by-election.