Today is Thursday, 2021-04-22
Some Icons by Dryicons
A year ago, I wrote two posts looking at the Covid-19 numbers for Canada.
The reality is much more complicated than either of these two simple models (exponential and logistics). But they are nonetheless still very useful to break things down into different parts:
I created a public spreadsheet to analyze all of this in more details. In particular, I use four different graphs to gain insights into where things are going.
This graph is a “smoothed out” version of the actual reported counts. Testing backlogs that get caught up later creates noise in the original data that I reduced using a 7-day running average, which seemed to be a good balance between details and noise level.
This graph represents the number of new cases each day. Mathematically, it's the first derivative of the previous graph. Numerically, I computed the slope of 5-day secants of the smoothed curve, again to reduce noise of the overall trend.
Here, we clearly see:
And the scary thing is that each wave seems to be bigger than the previous one.
When this graph is negative, the number of new cases each day is decreasing. When it's zero, the number of new cases each day is the same. And when it's above zero, the number of new cases each day increases each day.
We can see that in January, we started putting the breaks on the second wave, except we are now accelerating again towards a third wave.
This last graph represents the time (in days) that it would take to double the total number of cases were the trend to continue. Here, the vertical axis is a time scale (in days), not a number of infections.
A small number is bad because it means the total number of cases doubles in a short amount of time.
For example, between October and January, the doubling time was roughly 50 days, and looking back at the first graph, we can see that the number of cases doubled in about that time.
A constant doubling time means that the growth is exponential. An infinite doubling time means no more new cases. We can see that the doubling time of 200 days we had last month is starting to decrease, again indicating that we are starting a new wave.