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The election night time curve

May 9, 2022 - 09:30 -- Admin

I think those of us who have followed a lot of Australian elections have some instinctive sense of how election night progresses – when we should expect results to come in, and how quickly they do so.

But I thought I would dive into the data to actually map out the rate at which results flow in. The Australian Electoral Commission publishes a media feed on each election night, with a new XML file uploaded roughly once a minute throughout the night. This is the source of data for media outlets like the ABC and Channel 9 who run their own automated results analysis, but it has the benefit of giving us a snapshot of what the election results looked like at any point in time on election night (or the following days) at the last four elections.

While these trends may be affected by a big shift away from election day voting towards early voting in 2022, it’s still a useful starting point and an interesting way to look at how results flow.

For most of this post, I will be looking at how much of the total House primary vote has reported at any time, as a proportion of the final vote totals.

This first chart shows the rate at which House primary vote results came in for each state and territory at the 2019 election, based on Australian Eastern Standard Time (AEST).

Timezones will be the same for this election as in 2019, so this firstly gives you a sense of which states will come in when.

Very little had been reported by 7pm. Tasmania led the charge, with 9.2% at 7pm, and 55.6% by 8pm.

The three big east coast states are clustered closely together, but take longer than Tasmania. About 3-5% was reported by 7pm, which had reached 32-37% by 8pm. The remaining east coast jurisdiction, the ACT, took much longer. Barely 16% of the ACT vote had been reported by 8pm, putting them at least an hour behind their bigger neighbours.

South Australia has a half-hour delay compared to the east coast, but caught up to the big east coast states by about 8:45pm. 20% had been reported by 8pm, with 55.6% by 9pm.

The Northern Territory shares a timezone with South Australia, but it’s results come in much later. Almost 40% of the South Australian vote had been reported by 8:30pm, but but just 11.6% in the Northern Territory. The NT vote is much jumpier, likely due to the smaller number of booths and seats leading to less granular counting.

Western Australia is two hours behind the east coast, and an hour and a half behind the central timezone, so it comes in much later. By 9pm, just 3.4% of the WA vote has been reported. This is almost 40% as of 10pm, and has started to level off at about 63% as of 11pm.

The figures won’t be exactly the same this time, but some of the underlying factors should remain the same.

I’ve also made a chart showing the same information but adjusting for local timezones. This makes the results much more closely clustered.

Tasmania still has the lead, with the five mainland states following similar curves until about 8pm local time, at which point Western Australia and South Australia keep up the pace for longer while the count slows down in the big east coast states. The ACT trails behind until about midnight, while the NT starts slow but catches up around 9pm-10pm.

All of this data is just looking at the 2019 election, but now I wanted to do two things: look at the overall national picture, and compare it to the previous three elections.

The curves are very similar in shape. Very little is reported by 7pm, there is a big surge until 8pm, it slows down until 10pm, and not that much comes in after that.

But there is a gradual shift over the decade, with the pace of that early counting slowing down, and thus having less of a dramatic deceleration later in the night.

In 2010, 60% of the vote had been reported by 8:30pm. In 2019, only 40% had been reported by then, and it took until 10pm to get to 60%.

This also means the later hours have increased in importance. Only about 4% of the vote was reported between 10pm and 11pm in 2010. In 2019, it was more like 9.5% of the vote.

The charts are scaled to the final vote count, and they all end up roughly around 80-84% by 2am, although there has been a slight decline in this number.

All of this is consistent with the shift towards pre-poll voting. Pre-poll votes tend to come in later in the night, so an increased pre-poll vote should lead to a slower election night count.

In by-elections and smaller state elections we’ve seen a pattern of the election day votes coming in a rush, followed by a decent length break during which there is no new data, before the pre-poll votes come in. I don’t think federal elections have that sudden step change, because there is enough diversity of timezones and types of seats that means that the first pre-poll votes come in not long after the election day vote starts to peter out.

I suspect in 2022 we will see this curve flatten out even more, with more pre-poll voting, but also the final count at the end of the night should be lower, since postal votes won’t be counted on the Saturday.

Finally, I thought I would compare the 2019 election night primary vote curve to the two other sets of results we get on the night: two-candidate-preferred and Senate:

The other two types of data do come in later, and never reach the levels of completeness we see with primary votes.

The two-candidate-preferred count is about half an hour behind the primary vote early in the night, and that gap widens to about an hour by around 10pm.

Meanwhile we only start to see substantial counts for the Senate around 9pm-10pm, and it flattens out around midnight.

Hopefully all this will be useful in understanding the timing of election results on election night. I’m going to come back later this week with another post looking at how the votes for each of the parties change through the night, and how long they take to stabilise.