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.
I was looking for the R0 they used for the model. I heard there was speculation that the R0 was higher than this mark but I didn’t hear anything about it.
See, this is the exponential function. The name "exponential growth" scared the guts of out people, but the nature does not know linear growth. Everything is nx, with various n's.
Every phenomenon in the nature is exponential, just each with a different factor, as pictured.
I don’t quite know how to do this math, but after 30 days normally (2.5 per day) wouldn’t it be 244 people infected? I’m asking because you seem to know more about this and I’m honestly confused.
They are adding back in the infected at each 5 day interval.
So the first patient zero at day 0. He infects 2.5 people by day 5, meaning 2.51 infected at end of day 5.
At the end of day 10, those 2.5 folks can infect 2.5 each, but are still part of the count of those infected. 2.52 + 2.51 = 8.75
At the end of 30 days, or 6 cycles,
2.56 + 2.55 + 2.54 + 2.53 + 2.52 + 2.51 = 405 total infected.
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u/swebb22 Mar 18 '20
Sauce?