I did some analysis of epidemiology curves for coronavirus. This particular curve plots out the cumulative proportion of cases over time for a number of countries:
Each point on the line is a proportion of the total — which is why they all touch at the far right; all countries are at their daily cumulative maximum
(1.0) as of March 16th.
The graphs differ across counties in two important ways. First, they are shifted in time. This shows something we already know–that China and south-east Asia got hit with the infection first, and Western Europe and North America more recently.
More interesting is the shape of the curves. Notice that the rate of increase has been flattening out for China for some time. South Korea has is seeing a more recent flattening. Countries in Europe and North America are seeing a large increase now.
The most noteworthy line on this graph is Japan. Japan is seeing a slow and steady growth in cases, something that is typically not what infectious disease models predict. Usually growth, and often decline, tends to be nonlinear–a fast rise followed by a fast drop (and then a possible return with a lower amplitude). It’s hard to know what to make of this.
Is it because Japan is under-testing or under-reporting? Or is it that public health interventions were implemented very quickly and effectively in Japan? Only time will tell… Here’s the code for you to see for yourself.