As the last week of the 2019 election campaign got under way, the major polls were showing essentially the same picture. Each of them had Labor slightly ahead (either 51–49 or 52–48) on a two-party-preferred basis, and each had both the major parties polling less than 40 per cent of the primary vote. As always, how these figures translate into parliamentary seats, and how much they will change between now and election day, is being hotly debated.
Every election is unique, of course. But when we are trying to guess what might happen in the near future, looking at past patterns can help us see where the current campaign fits, and guide our weighting of likelihoods and probabilities. It also helps us see what has changed and what hasn’t.