Is this curve quadratic or exponential?

Point Conception · Jul 23, 2021

Does this curve look quadratic or exponential

Line graph titled Daily new confirmed COVID-19 cases for Thailand, April to July 2021, with a rising curve from near zero to about 14,000 cases per day, plus a bar chart of community cases below.

Point Conception · Jul 23, 2021

Phone screenshot of a forum reply with a partial quoted post, followed by a calculation of an exponential growth model dy/dt = ky, with the solution y(t) = y(initial) e^kt and k = 0.0972, giving y(63) = 982,266 total cases.

I got this from orange bar graph with dy/dt =ky. But with so many unknowns in cases reporting maybe a quadratic curve would be more accurate ?

fresh_42 · Jul 23, 2021

It looks exponential. And as soon as nature is involved, it is exponential anyway. The lockdowns have been so hard because they should break down exponential behavior. I think there are websites on which you can calculate SIR models. Have a look at
https://www.physicsforums.com/threa...th-and-other-curiosities.970262/#post-6164027

jedishrfu · Jul 23, 2021

Yeah, we know infectious disease follows an exponential curve always. However, data may not accurately reflect the curve, or may come in delayed, or vaccine efforts may blunt the effect and may make it look quadratic.

I think paper discusses these issues better and shows where sometimes a quadratic model comes out of the data:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8027562/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8027562/

Is this curve quadratic or exponential?

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