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2013 New South Wales Redistribution: Analysis of Draft Electoral Boundaries

2013 New South Wales Redistribution: Analysis of Draft Electoral Boundaries

Advice on legislation or legal policy issues contained in this paper is provided for use in parliamentary debate and for related parliamentary purposes. This paper is not professional legal opinion.
Background Paper No 01/2013 by Antony Green


This publication contains an assessment of the political impact of the draft electoral boundaries for New South Wales, released on Monday 17 June 2013. The draft boundaries are now open for public comments, with the Electoral Districts Commission set to finalise the redistribution later this year. Final boundaries will apply from the 2015 election.

It must be stressed that this publication does not provide predictions for the 2015 election. The estimated margins provided in this publication are best thought of as possible results of the 2011 election had that election been fought on the draft boundaries. The estimates cannot take into account the difference in candidate and campaign effort that would have occurred if the 2011 election had been fought on the new boundaries. The difficulty of splitting polling place catchment areas to match new electoral boundaries, as well as allocating declaration votes to new electorates, means the estimated margins should be treated as approximations.


To calculate the political impact of the new boundaries, the results of the 2011 election have been re-assigned to match the new electoral boundaries. This requires a series of assumptions to be made as part of the calculations. These assumptions concern whether votes are cast for candidates or parties, how to transfer polling places between old and new electorates, and how to deal with the declaration vote from old electorates.

Candidate versus Party Vote

An assumption has been made that votes are cast for parties rather than candidates. This is a reasonable assumption, but ignores the importance of popular sitting members. A well-known sitting member may poll higher than his or her party would have with a different candidate. New electoral boundaries can see areas added to an electorate where the party vote was not influenced at the last election by the presence of the sitting member.

The roll of sitting Independent members is even more difficult to take into account. None of the Independents elected at the 2011 election contested the areas added to their electorates by the redistribution, making it difficult to calculate precise two-candidate preferred margins.

Transferring Booths to Match the New Boundaries

The Electoral Districts Commission released lists of all transfers of enrolment between old and new electorates. The transfer of polling place results from old to new electorates has been guided by the enrolment transfers as well as the published maps. Where the transfers and maps suggest the catchment area of a polling place should be divided, an estimate has been made to divide the results of a polling place between new electorates.

Dealing with the Declaration Vote

For calculation purposes, all declaration votes (pre-poll, postal, etc) and votes cast at Sydney Town Hall (except those in the Sydney electorate) have been accumulated into a single total and transferred to new electorates.

These accumulated totals have been transferred to new electorates in proportion to the transfer of enrolment from old to new electorates. However, the vote by party in the declaration vote has been weighted to reflect the vote by party in polling places transferred between electorates.

As an example, the old electorate of Marrickville has been abolished and divided between the new electorates of Newtown and Summer Hill. The polling places in those parts of Marrickville transferred to Summer Hill voted more strongly for the Labor Party in 2011 than polling places transferred to the new electorate of Newtown. As a result, in dividing the declaration vote between Summer Hill and Newtown, the patterns of polling place results is reflected in the declaration vote transferred. Summer Hill has been allocated a higher proportion of Labor vote and lower proportion of Green vote from the divided declaration vote than has been transferred to Newtown.

By-elections and Changes in Party Membership

This publication is based on 2011 election results and does not use the results of the four by-elections held since 2011. The by-elections were in the National-held electorate of Clarence (November 2011), Labor-held Heffron (August 2012) and Independent held Sydney (October 2012) and Northern Tablelands (May 2013).

The Northern Tablelands by-election was won by the National Party. As a result, the electoral pendulum on page 5 does not show the seat as Independent held, and a National 2-party preferred margin based on the 2011 election is used.

Two-Party Preferred versus Two-Candidate Preferred Results

The two-candidate preferred count for an electorate is defined as the final count of votes between the two remaining candidates after the exclusion and distribution as preferences of votes for all other candidates. At each stage of the distribution of preferences, the candidate with the fewest votes is excluded and his or her ballot papers re-examined to determine the candidate with the next available preference. To achieve victory, a candidate must receive more than 50% of the total two-candidate preferred vote. Where a candidate achieves more than 50% of the vote before the final distribution, the two-candidate preferred count is continued to completion for information purposes.

The two-party preferred count represents a distribution of preferences between candidates representing the Labor Party and the Coalition. Candidates are again excluded based on lowest progressive vote, though at some point the second lowest candidate is excluded to retain candidates representing Labor and the Coalition. The two-party preferred count plays no part in determining the winning candidate but is used for information purposes.

In most cases, the two-party preferred result will be the same as the two-candidate preferred result. At the 2011 election, 66 of the electorates finished as two-party preferred contests between Labor and Coalition candidates. A separate 2-party preferred count was carried out in the other 27 electorates, allowing a 2-party preferred margin to be calculated for the 93 new electorates. The estimated new 2-party preferred totals are shown on the listing for each new electorate in this publication.

Calculating new 2-candidate preferred totals is more complex. In the most difficult example, the new electorate of Newtown includes transfers from three existing electorates, Heffron, Marrickville and Sydney. At the 2011 election, Heffron finished as a Labor-Liberal contest, Marrickville as a Labor-Green contest, and Sydney as a Liberal-Independent contest. No sensible 2-candidate preferred total is produced by amalgamating the 2-candidate preferred votes for these electorates.

In Balmain and Lake Macquarie, new 2-candidate preferred totals have been estimated to overcome this amalgamation problem. Other electorates, such as Davidson and Sydney, did not produce amalgamation problems and sensible 2-candidate preferred totals have been provided. Some new electorates, Goulburn being the best example, produce totals with separate Liberal and National entries in the 2-candidate and 2-party preferred totals. These cases can be simplified by simply adding the Liberal and National votes together.

Polling place two-party and two-candidate preferred results can be found in my publication “NSW Legislative Assembly Election 2011: Two-Party Preferred Results by Polling Place”, Background Paper No 1/2012, NSW Parliamentary Research Service.

Electorate Name Changes

Of the 93 Assembly electorates, 86 retain the same name, though some of those electorates have undergone extensive boundary changes. Seven electorate names have disappeared, and seven new names appear or re-appear on the state’s electoral map.

For the purposes of this publication, I have treated two electorates as being abolished, The rural electorate of Murrumbidgee has been abolished, and I have also treated the inner city seat of Marrickville as being abolished, with Marrickville forming the basis of two new inner-city seats, Newtown and Summer Hill. The Electoral Districts Commission chose to treat Summer Hill as a successor seat to Marrickville. Both seats are listed as abolished electorates on page 108.

The other name changes have come about to reflect changed geography. Burrinjuck becomes Cootamundra, Menai becomes Holsworthy, Murray-Darling becomes Murray, Smithfield is now known as Prospect, and Toongabbie is re-named Seven Hills.

Throughout this publication the new names for electorates will generally be used.

Acknowledgements and Disclaimer

All estimates have been calculated based on the actual results of the 2011 election and with reference to data and maps provided by the Electoral Boundaries Commission. My thanks go to the staff the NSW Electoral Commission and the Electoral Districts Commission. My particular thanks go to Paul Beeren for his work on calculating the enrolment transfers between old and new electorates.

However, responsibility for all calculations, and the assumption underlying them, must rest with the author.

Antony Green
June 2013