Table of Australian House Elections (IRV) 1949-2007

The following table was provided by Antony Green at ABC (Australian Broadcasting Co.) and has not been checked/verified by us. The Australian House (but not Senate) is elected by what in the USA is called "instant runoff voting" (IRV) but in Australia is called "the alternative vote."

House election cycles, Australia, 1949 through 2007
  Number of Seats where
Election #Seats Average #Canddts per Seat Combined Vote% for Minor Parties IRV "runoff" needed (i.e. no majority in 1st round) Plurality→IRV result "flip"
1949 123 n.a. 3.9 22 9
1951 123 n.a. 2.1 6 2
1954 123 n.a. 2.9 6 2
1955 124 n.a. 7.7 17 1
1958 124 n.a. 10.7 31 7
1961 124 n.a. 10.0 37 7
1963 124 n.a. 8.5 24 9
1966 124 n.a. 10.1 31 5
1969 125 n.a. 9.6 40 12
1972 125 n.a. 9.0 49 14
1974 127 n.a. 5.0 33 10
1975 127 n.a. 4.1 24 7
1977 124 4.1 12.3 46 4
1980 125 4.0 8.6 39 6
1983 125 4.2 6.9 31 2
1984 148 4.2 7.5 44 13
1987 148 4.1 8.1 54 4
1990 148 5.3 17.2 91 11
1993 147 6.4 10.8 63 12
1996 148 6.1 14.0 65 7
1998 148 7.5 20.4 98 7
2001 150 6.9 19.2 87 6
2004 150 7.3 15.7 61 8
2007 150 7.0 14.5 75 9
Total 3204 6.0 10.0 1138=35.5% 174=5.4%
Range (1949-2007) 123-150 4.0-7.5 2.1-20.4 4.9%-66.2% 0.8%-11.2%

Green remarks: As the above table shows, the number of seats requiring going beyond the first round of the instant runoff process increased substantially in the last two decades, mostly due to the rising vote% for minor parties (and the increasing number of candidates). The presence of party names on ballot papers since 1984 has also given voters more clues on who the minor parties represent. As anyone who has scrutineered will tell you, some voters give preferences to every other candidate on the ballot paper before finally making the choice between major party candidates.

Another remark: it is a theorem that, if at most 25% of IRV voters rank minor-party candidates top, then one of the top-2 parties will always win the election. Because the minor-party vote% has never exceeded 20.4% nationwide, it is not all all surprising to see massive 2-party domination in the Australian house. The last three elections in the table elected a total of zero minor-party seat-winners out of 450=150×3 total seats.


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