For 1 I’m not entirely sure but a couple of thoughts:
a) Just a week ago there were only 4 counties outside China which had enough cases to really analyse. One of these is Japan which could have misled any analysis. For Italy, S Korea and Iran there were only ~7-10 days of data. Between all that I think any analysis more than a week old would have really struggled to get an accurate picture of global behaviour.
b) Depending on what you’re trying to predict you might look at different sections of the graph.
I am specifically looking at the early outbreak numbers (highest fractional change per day). This is partly because I think this represents more of a natural understanding of the virus and partly because people are wanting to know what to expect in the US/UK etc.
If instead you look at the highest number of new cases per day section of the graph, then in China this happens from days 18-22. In this section the doubling time is 5-9 days. These numbers are less helpful IMO (in these sections the doubling times are constantly increasing so an exponential model won’t work very well) but it might give a farily good guess for what will happen in the next few days.
Between those 2 factors I can imagine other people getting other results.
Googling quickly I notice that at least one paper get similar results to me!
For 1 I’m not entirely sure but a couple of thoughts:
a) Just a week ago there were only 4 counties outside China which had enough cases to really analyse. One of these is Japan which could have misled any analysis. For Italy, S Korea and Iran there were only ~7-10 days of data. Between all that I think any analysis more than a week old would have really struggled to get an accurate picture of global behaviour.
b) Depending on what you’re trying to predict you might look at different sections of the graph.
I am specifically looking at the early outbreak numbers (highest fractional change per day). This is partly because I think this represents more of a natural understanding of the virus and partly because people are wanting to know what to expect in the US/UK etc.
If instead you look at the highest number of new cases per day section of the graph, then in China this happens from days 18-22. In this section the doubling time is 5-9 days. These numbers are less helpful IMO (in these sections the doubling times are constantly increasing so an exponential model won’t work very well) but it might give a farily good guess for what will happen in the next few days.
Between those 2 factors I can imagine other people getting other results.
Googling quickly I notice that at least one paper get similar results to me!