Re: [Phys-L] Finally ... normalized (by population) data, and Andorra

[brian whatcott <betwys1@sbcglobal.net>]

On 4/13/2020 10:54 AM, David Bowman wrote in part:
/snip/
> It appears that a simple logistic model gives an asymptotic y_∞ value 
> of around 32000 - 33000 US deaths (with much larger error bands) and 
> the date of the inflection point was sometime around April 8 - 9.
> Nevertheless I should mention that I doubt that the simple logistic 
> model is appropriate,/snip/ If, in the end, the model works out well 
> it would do so only by accident. One problem with a logistic function, 
> being the simplest function that has exponential growth at the left 
> side end and exponential decay to an upper bound at the right side 
> end, is that both the left side exponential growth and right side 
> exponential decay necessarily have the *same* exponential rate. /snip/ 
> There is absolutely no reason to expect any real contagion to possess 
> such symmetries--even when confined to local regional values. David Bowman
I found David's review helpful, particularly concerning the different 
exponents that may be needed, pre- and post- peak in a logistic function 
fit.
I touched on this need for a more nuanced logistic non linear fit in a 
note I wrote today:

https://community.wolfram.com/groups/-/m/t/1936520 I used the logistic 
model because it [accidentally?] fit the AIDS epidemic too - rather 
well! Thanks Brian W