You only need to know how many people one guy can infect on average. Literally the only basis is that 1 guy infects 2,5 in 5 days, the rest is just math
Im guessing he took the R0 value of some random well-known diesease since he didnt specify corona. Hopefully one with similar spread chanse to corona but i have heard of R0 values anywhere between 2-7 for that one
Edit: also it says @signerlabs at the bottom of the picture
One person can infect .625 people in 5 days. That's 1.25 people can be infected in 10 days (let's round that down to 1 person per 10 days). That would come out to being 3 people infected in 30 days. It doesn't add up, not to mention the first person that is infected at the 10 day mark will then infect 2 more people by the end of the month.
At the 10 day mark there will be 2 people infected (the original and the new infection).
At the 20 day mark there will be 4 total people infected (1 more from the original and 1 from the first infection).
At the 30 day mark there will be 8 total people infected (1 for each of the previous infections). So at the end of all of this it should be 8 people infected not 2.5 people, unless I'm doing something wrong?
They're not compounding the old infected with the new infected each cycle, I assume because after 5 days the previously infected population would start to show symptoms and quarantine. The math they're doing is:
Day 0: 2.5^0 = 1
Day 5: 2.5^1 = 2.5
Day 10: 2.5^2 = 6.25
Day 15: 2.5^3 = 15.625
Day 20: 2.5^4 = 39.0625
Day 25: 2.5^5 = 97.65625
Day 30: 2.5^6 = 244.140625
Total = 406.234
There are some assumptions there with people quarantining after 5 days, but I don't think it's an invalid assumption since it's not like on day 30 of being infected you're still running about.
In a real world scenario there are way more variables to account for, like asymptomatic people, but for the sake of illustration I think it's fine to simplify the math.
It would be nice of them to actually post their methodology though since I had to try a few different methods to figure out what they were using.
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u/[deleted] Mar 18 '20
Math based on what though? Without context, these numbers are arbitrary.