Analysis — What’s up with growth curves?
With all the talk about flattening the curve it’s important to track how Australia fares versus other countries. The following analysis looks at the latest figures and we look at Australia at a global level as well as how the states fare against each other.
NB: This article was written at 3:36pm AEST using the latest available source data. The delay in publishing is due to a limit in Medium of 3 articles per 24 hour period.
Growth since 100th confirmed case
When we look at the countries that have had exponential growth, some of the most commonly quoted ones to flatten their curves (and effectively get better control of the virus spread) have been China and South Korea.
As of the 28th March, when taking a look at where Australia is on this curve it looked there was some curve flattening.
However, as of the morning of the 29th March, we can see that the upward trend continues for Australia.
Further curve flattening
It’s expected that we won’t see much resulting from the self isolation and lock-downs imposed by the government due to the asymptomatic nature of some who get this virus. There are those who won’t record signs for at least 2 weeks so the effect of our strategies here will take time to see.
We’re not out of the woods yet though as our curve could still grow higher. The Australian government here spoke about an expectation that 20–30% of people who not listen to the calls to socially distance themselves when out. So we will hopefully see data curve towards a better angle for Australia in the near future.
When looking for curves flattening, another way to view this is by the number of new cases over a fixed period. The idea behind this is that whilst in the middle of an exponential growth rate curve, it is hard to tell when something is slowing down or not. The idea to look at the data this way comes from the YouTube channel ‘Minute Physics’ and their video ‘How to tell if we’re beating Covid-19' (https://www.youtube.com/watch?v=54XLXg4fYsc).
In their example they look at South Korea and how its 3 day average showed signs of slowing down since its first case.
Initially, whilst still on the red curve, those looking at South Korea could likely assume that the curve would continue exponentially upwards
However, if we look at confirmed cases as a moving average, thete are signs of inflection shown.
In the example I have built I look at confirmed cases since a country hit their 100th (so as to baseline them) and use a 7 day average (e.g. what was the last week of total confirmed cases per country on a rolling basis). Also, the following analysis was done using data from 27th March as this part of the analysis was written on the 28th March
We can see that Italy was on exponential growth territory but ended up flattening their curve recently.
The US has more to worry about though on their trajectory. The Y-axis shown here is average cases per week so per the latest data it was getting 84k new confirmed Covid-19 cases per week!
Overlaying both we see that the US is on a far steeper trajectory than Italy, and so far, is climbing.
South Korea, among all this, has done much better at flattening its curve and stands in stark contrast
Australia, when we compare it to South Korea looks steeper in its angle but taking this weekly average does not account for the slight curve in growth we saw above on the log-scale version of this. We can also see here how South Korea has also brought down its average weekly cases too.
For these 7 day moving average versions, they can tell us a better picture than relying on a few single points. Italy saw its daily confirmed cases/deaths slow down last week only for it to climb again a few days later. It’s good to look at this data in these other ways to get a clearer picture.
Focusing on Australian states
Looking at Australia and creating a baseline for when all states got their first cases we can see that NSW is far and away the leader of the pack with 1,405 cumulative cases as of last night. They are more than double the next states (Victoria 574, Queensland 555)
Looking at things on log scale allows us to scale up the smaller figures so they’re more comparable. We can see that all states have similar trajectories.
For more analysis on Covid-19 then check out the Corona Virus section of our blog here: https://medium.com/prosperity-advisers-dna/coronavirus/home.
Stay safe out there folks!
