third party presence of SA Best is eating in to the Liberal vote somewhat greater than the Labor vote. Background Overview There were fourteen political parties registered with the Electoral Commission of South Australia at the time of the election, which were consequently eligible to field candidates for election. Aside from the major parties (Labor and Liberal parties), SA-Best, which polled higher figures than the major parties on occasion, ran in 36 seats, more than the 24 theoretically required to form government. The fourteen parties registered with the Commission were Advance SA, Animal Justice Party, Australian Conservatives, Child Protection Party, Danig Party of Australia, Dignity Party, the Australian Greens SA, Australian Labor Party (SA Branch) and Country Labor Party, Liberal Party of Australia (SA Division), Liberal Democratic Party, the National Party of Australia (SA) Inc, Nick Xenophon's SA-BEST, and Stop Population Growth Now. Since the previous election, six new parties had registered: Danig Party of Australia, Animal Justice Party, Nick Xenophon's SA-BEST, Australian Conservatives, Advance SA and the Child Protection Party. Four were no longer registered: FREE Australia Party, Fishing and Lifestyle Party, Multicultural Progress Party and the Family First Party. Voting changes Like federal elections, South Australia has compulsory voting and uses full-preference instant-runoff voting for single-member electorates in the lower house. However, following similar Senate changes which took effect from the 2016 federal election, South Australia's single transferable vote in the proportionally represented upper house changed from group voting tickets to optional preferential voting − instructions for above the line votes were to mark '1' and then further preferences optional as opposed to preference flows from simply '1' above the line being determined by group voting tickets, while instructions for voters who instead opt to vote below the line were to provide at least twelve preferences as opposed to having to number all candidates, and with a savings provision to admit ballot papers which indicate at least six below-the-line preferences. Previous election The 2014 election resulted in a hung parliament with 23 seats for Labor and 22 for the Liberals. The balance of power rested with the two crossbench independents, Bob Such and Geoff Brock. Such did not indicate who he would support in a minority government before he went on medical leave for a brain tumour, diagnosed one week after the election. University of Adelaide Professor and Political Commentator Clem Macintyre said the absence of Such virtually