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# [NB] Logistic Model for Quarantine Controlled Epidemics

Posted 4 years ago
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Posted 4 years ago
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Posted 4 years ago
 I find a logistic function helpful in conjunction with a non linear curve fitter. It does have a short-coming. After locating the probable peak rate from a cumulative time series, it is likely to underestimate the decay portion of the rate plot. This is true where the exponential for the upper half is in fact on a longer time constant, so the rate has a longer decay time. All in all, it is a useful approach - and this was true when it was used to model the AIDS epidemic last century.
Posted 4 years ago
 I received some helpful ideas from David Bowman at Georgetown. He understood my need for something better than the logistic function which uses thesame exponential for growth and decay to a high limit. At the cost of a fourth parameter, he provided a function which can fit a curve that grows and levels on different time constants. Sadly, the only curve where this is presently finding a use is US Deaths for whatever reason. US, Cases and Oklahoma Cases and Deaths are best fitted with a linear slope presently. This is the function: deaths = k1 / (1+ aexp(ab*(Start day number - present day number)))^(1/c) Four parameters. Here is what a plot looks like:By contrast here is a linear US CASES plot:
Posted 4 years ago