On 4/12/20 1:47 PM, bernard cleyet asked about the assertion:
the growth of the virus should be independent of the size of the country.
Well, yes and no.
All physics is local. So is virology. The disease spreads locally,
under the control of local conditions. So naïve models of how "a
country" is affected are dead on arrival. Instead one should model
each locality separately.
HOWEVER ... AFTER all those models have been run, you can sum the
results across the whole country. In most places at most times,
the result is likely to be what we all an extensive variable.
That is, if you put two identical countries side by side, you
get twice as much population and twice as many deaths. So
normalizing per capita mostly makes sense.
The one exception -- a huge exception -- is China. The outbreak
started in one place, not everywhere. And they mostly confined
the outbreak to Hubei. So it makes sense to normalize by the
population of Hubei, not the whole country.
One concludes that they did a terrible job in Hubei, but did
fairly well elsewhere.