Tricksy!

The graph above is extracted from the presentation given during the UK government’s Covid-19 press conference on Wednesday 6 May.  It  shows the cumulative number of deaths per million population for a number of countries. 

The UK is doing badly on that measure, as it’s just below Spain. But it doesn’t appear to be doing very much worse than the US. Neither does the difference between Germany and the UK  seem fantastically dramatic. It appears that Japan and South Korea are doing quite badly as well.

However, the graph is using a logarithmic scale (or log scale), which is a way of displaying numerical data over a very wide range of values in a compact way—typically the largest numbers in the data are hundreds or even thousands of times larger than the smallest numbers. The numbers 10 and 100, and 100 and 1000 are equally spaced. 

If the graph is redrawn using a standard scale, things look dramatically different:

The UK is still the second worst, but look how the gap between the UK (red line) and the USA (brown dashes) has dramatically widened, as has the gap between the UK and Germany (amber line). The death rates in Korea (blue line) and Japan (hidden by Korea) appear to be virtually zero. They’re not of course, but they aren’t yet in double digits.

Using a log scale tells a completely different story, and can be highly misleading.  I wonder whether the original graphic was deliberately designed to be misleading?

Note: The government’s figures came from John Hopkins University and Public Health England (PHE).  Mine are from the European Centre for Disease Prevention and Control (ECDC), so they might be slightly different.