8 November 2001

The election night computer system

Once the votes are counted at each polling place after 6pm, the results are telephoned through to the AEC Divisional Office where they are entered into the AEC's computer system. Because all of the AEC's 150 Divisional Offices are 'on-line', results data will be available in the National Tally Room (NTR) and from the virtual tally room almost immediately. First results are expected from about 6.30pm (Canberra time).

In communicating the results of the election to the Australian public, members of the media will be assisted by the AEC's computer network, in addition to their own informal channels and computer packages. AEC staff will be available at the NTR in Canberra to provide assistance in using the AEC's computerised election night management system screens.

The computer enquiry screens

The AEC provides the television networks and AAP with a direct feed of election results from the election night computer system. For other members of the media, access to results is gained through the enquiry screens of the computer system available at the NTR.

The AEC also provides terminals to the political parties at the NTR, and to the Prime Minister and Leader of the Opposition at a location of their choice.

The enquiry screens display the results in a number of ways for both the House of Representatives and Senate elections.

Analysing the results and matched polling places

Over many elections, analysts have made an art form of interpreting the progressive figures as they enter the NTR. In the past, as early results became available there were obvious biases because of the small size of the sample of results.

In 1990 the matched polling place method was introduced and added another element to election night analysis. The matched polling place method effectively eliminates bias after approximately 10-15% of the votes are counted in any particular division. At the 2001 election, the AEC's computer system will again provide swings based on matched polling places, as well as the two candidate preferred count.

Matched polling places and the two candidate preferred count

The matched polling place method is applied in the AEC's election night computer system in two ways: to first preference votes and also to the two candidate preferred (TCP) figures.

For first preference votes, the number of votes for the current election for each candidate is accumulated as each polling place is entered into the system. As each polling place is entered, the system extracts the result from the previous election, and when the divisional results are displayed the percentage of the current votes received by each candidate is compared with the percentage from the previous election for the same polling places. The difference between the two percentages is expressed as a percentage swing to or away from the candidate. (Where an independent candidate, or a political party is contesting a division for the first time, there will be no historical votes and the swings displayed for this candidate will be the same as their first preference percentage.)

The matched polling place method as applied to first preference votes is a useful guide, and in cases where one candidate is likely, on the basis of the matched first preference swing, to get more than 50% of first preferences, it is sufficient to call the result in that division. However, in those divisions where preferences need to be distributed to determine the outcome, the first preference swing is not enough. The use of matched polling places for the two candidate counts works as follows.

As the indicative TCP vote for the current election is entered, the system combines the historical and current TCP votes in the same way as it does for first preferences.

The system calculates a TCP swing on the basis of the sample of polling places entered in the system, and making use of the tendency for swings to be uniform within a division. This swing is then applied to the final TCP result for that division from the previous election, giving us the predicted TCP swing for each candidate.

Virtual Tally Room

On election night the AEC hosts a 'virtual tally room' (an election results system) from their website. The election website can be accessed through www.aec.gov.au. From this website people can access results from their home computers as they are received in the NTR.

After election night the AEC's website will continue to provide results updates until the count is finalised.