"Darwin was the first to use data from nature to convince people that evolution is true, and his idea of natural selection was truly novel. It testifies to his genius that the concept of natural theology, accepted by most educated Westerners before 1859, was vanquished within only a few years by a single five-hundred-page book. On the Origin of Species turned the mysteries of life's diversity from mythology into genuine science." -- Jerry Coyne
Saturday, April 4, 2020
Coronavirus - Interesting math lesson - Exponential growth and epidemics
A good time for a primer on exponential and logistic growth, no?
Home page: https://www.3blue1brown.com
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Excellent visualization of this kind of growth from Minutephysics and Aatish Bhatia:
https://www.youtube.com/watch?v=54XLX...
Data source: https://www.worldometers.info/coronav...
Some have (quite rightfully) commented on how you shouldn't look at the R^2 of linear regressions on cumulative data since even if the changes from one day to the next are completely random, the totals they add up to wouldn't be independent of each other. Since the derivative of an exponential should also be an exponential, we could instead run the same test on the logarithms of the differences from day to day, which in this case gives R^2 = 0.91.
While this video uses COVID-19 as a motivating example, the main goal is simply a math lesson on exponentials and logistic curves. If you're looking for a video more focused on COVID-19 itself, I'd recommend taking a look at this one from Osmosis: https://youtu.be/cFB_C2ieW5I
Extrapolation xkcd: https://xkcd.com/605/
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These animations are largely made using manim, a scrappy open source python library: https://github.com/3b1b/manim
If you want to check it out, I feel compelled to warn you that it's not the most well-documented tool, and it has many other quirks you might expect in a library someone wrote with only their own use in mind.
Music by Vincent Rubinetti.
Download the music on Bandcamp:
https://vincerubinetti.bandcamp.com/a...
Stream the music on Spotify:
https://open.spotify.com/album/1dVyjw...
If you want to contribute translated subtitles or to help review those that have already been made by others and need approval, you can click the gear icon in the video and go to subtitles/cc, then "add subtitles/cc". I really appreciate those who do this, as it helps make the lessons accessible to more people.
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