Before I explain voting in the Australian Senate, perhaps I will first explain the House of Representatives.

The House of Representatives consists of all the “local members”. Each electorate has one local member. The aim is to get the member who is approved of by a majority of voters. To do this, a candidate needs 50% + 1 votes to get elected. If no candidate gets 50% + 1 of first preference votes, preferences are distributed – beginning with the candidate with the least number of votes – until one candidate has 50% + 1 of the votes. Notice this is guaranteed to give a result: when only two candidates are left, one of them will have at least 50% of the formal votes. (Unless there is a tie, but I’ve never heard of that happening in Australia). And if any candidate reaches 50%+1, it is impossible for any other candidate to, so there can only be one winner.

The Senate is very different because each “seat” is a state, and each state elects 6 senators at a time. To get elected to be a senator, a candidate needs to receive a seventh of the vote + 1, i.e. about 14.3%. This amount (14.3%) is called a “quota”. Notice again this is guaranteed to give a result: if six candidates have 14.3%, it is impossible for anyone else to get 14.3%.

You might think that, as in the House of Representatives, we distribute the preferences of the candidates with the least votes, until we get a result. But there is a complication: some candidates receive *more* than a quote of their votes. When this happens, the excess votes need to have their preferences distributed. So for instance, if a candidate receives 20% of the vote, then 20% – 14.3 = 5.7% must be distributed as preferences. But there is a further complication: whose preferences do we distribute? So for instance, if a quota is 143000 votes, and the candidate receives 200000 votes, which 57000 ballots do we choose?

The answer is we distribute them all! – but they are weighted. So all 200000 votes are distributed, but each only has a “weight” of 57000 / 200000 = 0.285 of a vote.

It sounds complicated – and it is – but it guarantees that the exact correct number of votes are redistributed. But how they ever did this in the days before computers is beyond me.

So that it why we need preferences in the Senate voting ticket. But is Senate voting too complicated? Can it be made simpler? That has been the problem for Australia, and is the subject of my next post.