Re: [math-fun] Covid19 R_e considered misguided
Once again, the use of 'average' in the phrase 'average reproduction number' presumes that the numerical value of 'average reproduction number' has some relevance to something or other in the real world. If such a numerical value can vary from 0.9-100, that fact would belie any commonsense notion of 'average' -- meaning 'ordinary' or 'typical'. But wait, it gets much worse! This numerical value R0_whatever-you-want-to-call-it is used as the *base* for an exponential function ! I.e., we're looking at an exceedingly fat-tailed distribution of numbers (R0)^some-exponent, so any hope of 'fitting' data to such a mess is out of the question. But models that can't fit data, can't predict anything. Models that cannot predict anything are no longer science, but quackery aka witchcraft. Is it any wonder that none of these 'models' can predict even an order of magnitude of infection, much less even 1 significant (decimal!) digit? The next article I read that quotes some PhD 'expert' which refers to this R0 nonsense will cause me to vomit. Perhaps those on this list will agree that proofs should end with 'QED', not 'PhD'. At 08:30 AM 5/22/2020, Michael Kleber wrote:
Just for clarity of terminology:
The epidemiological definition of R0 is the average reproduction number *in a completely susceptible population*.
H.B.: But models that can't fit data, can't predict anything. Me: Completely agree, but will say: SIR does predict exponential decay given data about exponential rise. Both are governed by the same shape parameter. On the other hand, SIR *does not* predict a plateau. H.B.: Perhaps those on this list will agree that proofs should end with 'QED', not 'PhD'. Me: The current PhD system does not inspire too much confidence, but I'm not sure how much better it is to trade 'PhD' for 'QED', especially in messy circumstances. Anyways most people who write QED have a PhD, so what are you really saying? We need experts with training in formal mathematics? The other issue is that QED is a Latin abbreviation, so it is very exclusive to elite westerners. Someone like Madhava would never think of ending an idea-in-verse with QED. Is this a reason for taking away credit from him? Elite westerners unequivocally answer yes. Is that answer fair? H.B.: The next article I read that quotes some PhD 'expert' which refers to this R0 nonsense will cause me to vomit. I feel the same way when I read almost any academic paper, but have found the attitude of "appreciating it for what it's worth", and usually that is more than nothing. The old adage is "don't throw the baby out with the bathwater". --Brad On Fri, May 22, 2020 at 11:00 AM Henry Baker <hbaker1@pipeline.com> wrote:
Once again, the use of 'average' in the phrase 'average reproduction number' presumes that the numerical value of 'average reproduction number' has some relevance to something or other in the real world.
If such a numerical value can vary from 0.9-100, that fact would belie any commonsense notion of 'average' -- meaning 'ordinary' or 'typical'.
But wait, it gets much worse!
This numerical value R0_whatever-you-want-to-call-it is used as the *base* for an exponential function !
I.e., we're looking at an exceedingly fat-tailed distribution of numbers (R0)^some-exponent, so any hope of 'fitting' data to such a mess is out of the question.
Models that cannot predict anything are no longer science, but quackery aka witchcraft.
Is it any wonder that none of these 'models' can predict even an order of magnitude of infection, much less even 1 significant (decimal!) digit?
The next article I read that quotes some PhD 'expert' which refers to this R0 nonsense will cause me to vomit.
Perhaps those on this list will agree that proofs should end with 'QED', not 'PhD'.
At 08:30 AM 5/22/2020, Michael Kleber wrote:
Just for clarity of terminology:
The epidemiological definition of R0 is the average reproduction number *in a completely susceptible population*.
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